/* -*- coding: utf-8 -*-
 *
 * 1101.cc:  No.1101 鼻水 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

typedef long long ll;

/* global variables */

/* subroutines */

/* main */

int main() {
  int v, t, p;
  scanf("%d%d%d", &v, &t, &p);

  ll w = (ll)v * (p + 1);
  t--;
  ll r = w / t * (t + 1) + (w % t > 0 ? w % t + 1 : 0);
  printf("%lld\n", r);
  return 0;
}