#include<iostream>
using namespace std;
int main()
{
	int x,y,n;
	cin>>x>>y>>n;
	if(n>(y/x)){
		if(n>(y/x)&&n<=10) cout<<y-1;
		else if(n>(y/x)&&n>10) cout<<(y-1)+(n-10)*(x-1);
	}
	if(n<(y/x)) cout<<n*(x-1);
	return 0;
}