#include <algorithm>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define REP(i,s,n) for(int i=(int)(s);i<(int)(n);i++)

using namespace std;
typedef long long int ll;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef pair<int, int> PI;



int main(void){
  ll a, b, t;
  cin >> a >> b >> t;
  ll mi = (t + a - 1) / a * a;
  for (ll x = 0; x < a * b && x < t + b; x += b) {
    ll rem = t - x;
    ll tmp = x;
    if (rem > 0) {
      tmp += (rem + a - 1) / a * a;
    }
    mi = min(mi, tmp);
  }
  cout << mi << endl;
}