#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;
int m, t, s, sum;
int main(){
    cin >> m >> t >> s;
    sum = (m * t - s) / t;
    if (t < 0)
    {
        cout << "0\n";
        return 0;
    }
    if (t == 0)
    {
        cout << "0\n";
        return 0;
    }
    cout << sum;
    return 0;
}