Code:

#include <bits/stdc++.h>
using namespace std;
int main(){
    long long x,y,n;
    cin>>x>>y>>n;
    if(n%10==0) cout<<(n/10)*(y-1)<<endl;
    else cout<<(n/10)*(y-1)+(n%10)*(x-1)<<endl;
    return 0;
}

只有80pts.Why?