#include <bits/stdc++.h>
using namespace std;
using ll = long long;

ll a, b, k;

ll f(ll n){
  ll m = a*b/gcd(a, b);
  return n/a + n/b - n/m;
}

int main(){
  cin >> a >> b >> k;
  ll l = 0; ll r = 1e18;
  while(r-l>1){
    ll mid = (l+r)/2;
    if(f(mid)<k) l= mid;
    else r = mid;
  }
  cout << r << endl;
  return 0;
}