SCU 4440 Rectangle (思维+暴力)

#include <iostream>
#include <cstdio>
#include <cmath>
#define ll long long
using namespace std;

int main()
{
    ll n,m,k;
    while(scanf("%lld %lld %lld",&n,&m,&k)!=-1)
    {
        if(k<4) cout<<"0"<<endl;
        else
        {
            if(n>m) swap(n,m);
            ll ans = 0;
            for(ll x=1;x<=n;x++)
            {
                ll y=min(m,(k-2*x)/2);
                if(y<0) break;
                ans=ans+((n-x+1)*(2*m-y+1)*y)/2;
            }
            cout<<ans<<endl;
        }
    }
    return 0;
}