#include <iostream>
using namespace std;

int main(){
  long A,B,T,N,result = 10000000000;
  int A_times,B_times,ab_times=0;               //T=A*B*ab_times+N | N < A*B

  cin >> A>>B>>T;
  
  ab_times = T/(A*B);
  if(ab_times>1)ab_times--;
  N = T-A*B*ab_times;
 
  for(B_times = 0;B*B_times<N+B;B_times++){   
    A_times = (N-B*B_times)/A;                 
    if(A_times < 0)break;                       //A_times cannot be negative
    
    if((A*A_times+B*B_times)<N) A_times++;
    result = min(result,A*A_times+B*B_times);
    //cout << A_times<< "  "<< B_times<<"   "<< result<<endl;
  }

  cout << result + A*B*ab_times << endl;

}