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