1 #include<bits/stdc++.h> 2 using namespace std; 3 typedef long long LL; 4 5 int main() { 6 LL a,b;cin >> a >> b; 7 if (a == b) cout << (a * b - 1) / 4; 8 else cout << (a - 1) * (b - 1) / 4; 9 return 0; 10 }
原文：https://www.cnblogs.com/mjtcn/p/9277349.html
