Rarely does diplomacy sound this mathematical.
Officials from North Korea, South Korea, and the United States will sit down in New York on Jan. 29 for a "three-way briefing" that is intended to persuade the North Koreans to participate in "four-way talks," which would also include China. But as diplomats and analysts here agree, what really interests North Korea are "two-way" discussions with the US.
The object is to convince one of the most isolated and erratic governments on the planet that the path to peace and prosperity lies in talking directly to its South Korean neighbor. Along the way, US and South Korean officials want to make sure that North Korea keeps its nuclear program peaceful.
Given North Korea's track record, analysts and officials in South Korea's capital are pessimistic. As recently as last fall, South Korean security forces hunted down commandos that North Korea sent by submarine to infiltrate the South.
"Talk is better than no talk, but whether this talk is progress - we'll have to wait and see," says Yang Sung Chul, a member of South Korea's National Assembly and a scholar of the North.
A senior South Korean government official, speaking on condition of anonymity, says diplomats and officials are not trying to dampen expectations ahead of the Jan. 29 meeting. "The pessimism may be based on reality," he says with an apologetic smile.
The parties are pushing for Chinese involvement because Beijing is North Korea's only major ally. Hopes are high that China will pressure North Korea into reconciliation with the South, although officials in Seoul admit Beijing hasn't exerted much pressure so far.
Indeed, there seem to be few positive feelings here about the immediate possibilities for reconciliation on this divided peninsula, which hosts the world's most militarized border and 37,000 US troops.
North and South Korea officially remain at war, since their 1950-1953 conflict ended in an armistice and not a peace treaty.
The North's economy is shrinking and the country has recently suffered food shortages, although it has been difficult for observers to make reliable assessments in a closed Communist country.
Several years ago there was a sense of anticipation here about the potential of a unified Korea.
But the costly and problematic process that Germans have undergone in unifying their once-divided country has convinced many South Koreans that they should avoid a rapid absorption of their northern neighbor.
More recently, North Koreans have proven to be difficult and unpredictable negotiating partners.
A good example of North Korea's behavior took place in the summer of 1995, when South Korean President Kim Young Sam responded to reports of North Korean food shortages by offering 150,000 tons of rice. South Korea agreed to pack the rice in unmarked bags so that the North Korean government would not appear to be accepting handouts from its enemy.
But the North then embarrassed the South Korean government by detaining a seaman from a ship delivering the rice and accusing him of spying. "The moment the rice was discharged in North Korea, they just slapped our face," the official recalls.
North Korea is most notorious for its nuclear program. In the early 1990s, US officials and an international monitoring group said the North might be preparing to produce atomic weapons.
That concern has diminished since October 1994, when the North agreed to halt its existing program in exchange for supplies of fuel oil and two brand-new nuclear reactors that the US, South Korea, Japan, and other countries are now providing.
The technology in the new reactors is less capable of generating nuclear material suitable for weapons. Ensuring that this deal goes through is one reason South Korea and the US feel they must continue encouraging North Korea to sit down at negotiating tables, say Western and Korean diplomats.
One South Korean foreign ministry official, also speaking on condition of anonymity, puts it starkly: "Unless we engage North Korea, the chance of war increases - everyone knows that."
The North apparently sees some value in dealing with the US. North Korea's state-run news agency consistently trumpets official contacts with the US government as evidence of the legitimacy and stature of its regime. Officials from South Korea and the US say the North has to be coaxed and cajoled each step of the way in its diplomatic encounters.
Late last year, for example, the country issued an unprecedented apology for the submarine incident last fall. But North Korea did not take this step out of any desire to placate South Korea, a government it characterizes as a US "lackey."
Instead, according to Western observers in Seoul who monitor relations between Washington and Pyongyang, the North Korean capital, the US is allowing an American company to proceed with a barter deal with the North that will provide it with some much-needed grain.
US officials also agreed to participate in "two-way" talks with North Korean officials that are expected to follow next week's "three-way" session.
Officials are not confident that the "four-way" process - which the South Koreans hope will lead to reduced tensions and an opening of North Korea's closed economy - will ever take place. It all seems to depend on how the North can be enticed.
At the meeting in New York next week, says the South Korean official, "we will explain to North Korea what they will get" if they go along.