LYDSY 3505
题目大意
暂无
题目解法
暂无
RTFC
//http://blog.csdn.net/popoqqq/article/details/39779647
#include <cstdio>
int gcd(int x, int y) { return y == 0 ? x : gcd(y, x % y); }
int main()
{
int m, n;
scanf("%d%d", &m, &n);
m++, n++;
long long ans = m * n;
ans = ans * (ans - 1) * (ans - 2) / 6;
for (int i = 0; i <= m; i++)
for (int j = 0; j <= n; j++)
if (i || j)
ans -= (i && j ? 2ll : 1ll) * (gcd(i, j) - 1) * (m - i) * (n - j);
printf("%lld", ans);
return 0;
}