代码

#pragma GCC optimize(2)
#include<bits/stdc++.h>
long long a, b;
#define getchar getchar_unlocked
#define putchar putchar_unlocked
template <class T>
inline void _read(T &x)
{
	x = 0;
	char t = getchar();
	while(!isdigit(t)) t = getchar();
	while(isdigit(t))
	{
		x = x * 10 + t - '0';
		t = getchar();
	}
}
template <class T>
inline void print(T x)
{
	if(x < 0)
	{
		putchar('-');
		x = -x;
	}
	if(x > 9)
		print(x / 10);
	putchar(x % 10 + '0');
}
int main()
{
	_read(a), _read(b);
	print((a - 1)*b - a);
	return 0;
}

评测结果