#include <queue>
typedef long long ll;

#include <cstdio>
inline int getInt(){ int s; scanf("%d", &s); return s; }

#include <set>

using namespace std;

int main(){
  const int a = getInt();
  const int b = getInt();
  const int t = getInt();

  if(a == 1){
    printf("%d\n", t);
  }else{
    int ans = (t + b - 1) / b * b;
    if(b < 1000){
      vector<int> memo(a);
      for(int c = 0; c <= t; c += b){
        const int diff = t - c;
        if(memo[diff % a]) break;
        memo[diff % a] = 1;
        ans = min(ans, c + (diff + a - 1) / a * a);
      }
    }else{
      for(int c = 0; c <= t; c += b){
        const int diff = t - c;
        ans = min(ans, c + (diff + a - 1) / a * a);
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}