Number 0 is written on the board. Two players alternate writing signs and numbers to the right, where the first player always writes either \plus{} or \minus{} sign, while the second player writes one of the numbers 1,2,...,1993,writing each of these numbers exactly once. The game ends after 1993 moves. Then the second player wins the score equal to the absolute value of the expression obtained thereby on the board. What largest score can he always win? modular arithmeticpigeonhole principleabsolute valuecombinatorics unsolvedcombinatorics