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;

    }

}