x^2 + y^2 - 2x + 2y = -2 移项
x^2 - 2x + 1 + y^2 + 2y + 1 = 0
( x - 1)^2 + (y+1)^2 = 0;
所以x - 1 = 0,y + 1 = 0,即 x = 1,y = -1
所以x^2007 + y^2008 = 1 + 1 = 2