Black-white Board Game

Both Fedya and Alex love playing games. One of their favorite games is playing with permutations. Description of game is given below. Initially, they have a N x N matrix with all cells being white. Before starting the game, Alex colors the matrix in following way. he chooses N pair of integer L[i], R[i] denoting that in the i-th row, columns from L[i] to R[i] (1 - based indexing) are colored bla