#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for (int i=0;i<(int)(n);i++)
template <typename T> bool chmax(T &a, const T& b) {if (a < b) {a = b; return true;}return false;}
template <typename T> bool chmin(T &a, const T& b) {if (a > b) {a = b; return true;}return false;}
const int MOD = 1000000007;
ll x = 10000000000;

int main(){
  double x,y,z;
  cin>>x>>y>>z;
  double a = y/x;
  if(ceil(z*a)!=floor(z*a))cout<<int(z*a)<<endl;
  else cout<<(int)z*y/x-1<<endl;

}

#include<bits/stdc++.h>
using namespace std;


int main(){
	int a, b, c;
	cin>>a>>b>>c;
	cout<<21-(a+b+c)<<endl;	
	return 0;
}