一道贪心题，尽量横着切或竖着切，实在不行在交叉切

#include<iostream>
#include<stdio.h>
using namespace std;

int main(){
 //   freopen("in.txt","r",stdin);
    long long n,m,k;
    while(cin>>n>>m>>k){
        if((n+m-2)<k){
            printf("-1\n");
            continue;
        }
        long long max=0,t;
        if(n>m){
            t=m;m=n;n=t;
        }
        long long ans;
        if(m>=(k+1)){
            ans=(n/(k+1)*m)>(m/(k+1)*n)?(n/(k+1)*m):(m/(k+1)*n);
        }
        else{
            ans=(m/(k-(n-1)+1))>(n/(k-(m-1)+1))?(m/(k-(n-1)+1)):(n/(k-(m-1)+1)) ;
        }
        cout<<ans<<endl;
    }
}