#include<bits/stdc++.h>
using namespace std;
using LL=long long;
using ULL=unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

ULL GCD(ULL a,ULL b){ return b?GCD(b,a%b):a; }

ULL A,B,K;
ULL G;

bool solve(ULL x){
  ULL a=x/A, b=x/B, g=x/G;
  ULL c = a+b-g;
  return c<K;
}

int main(){
  cin>>A>>B>>K;
  G=A/GCD(A,B)*B;
  ULL l=0, r=2000000000000000000;
  while(r-l>1){
    ULL m=(l+r)/2;
    (solve(m)?l:r)=m;
  }
  cout<<r<<endl;
  return 0;
}