If A losses any of i - 1 or i - x or i - y game then he will definitely win game i
if ( i - 1 >= 0 and ! dp [ i - 1 ] ) dp [ i ] = true ; else if ( i - x >= 0 and ! dp [ i - x ] ) dp [ i ] = true ; else if ( i - y >= 0 and ! dp [ i - y ] ) dp [ i ] = true ;