#include <iostream>
#include <set>
using namespace std;
int main(){
  int a,b,t;cin>>a>>b>>t;
  set<int> A;
  int i = 0;
  for(; t >= b*i; i++){
    if(A.count((t-b*i)%a))break;
    A.insert((t-b*i)%a);
  }
  int mn = b*i-t;
  for(auto x: A){
    if(x == 0)mn = x;
    else mn = min(mn,a-x);
  }
  cout << mn+t << endl;
}