int matrix[X][Y] = {0}; int max = 0; for(int i = 0; i < X; ++i) for(int j = 0; j < Y; ++j) cin >> matrix[i][j]; for(int i = 0; i < X; ++i) for(int j = 0; j < Y; ++j) max = matrix[i][j] > max ? matrix[i][j] : max; matrix[0][0] = max;