/*
TASK: minjumps
LANG: C++
*/
#include<iostream.h>
long otg,a,b,n,flag,min=2000000000;
int main()
{  cin>>a>>b>>n;
   if(n%a==0 &&  n/a<min) { otg=n/a; min=otg;}
   if(n%b==0 && n/b<min) { otg=n/b; min=otg;}
   if(n%(a+b)==0 && n/(a+b)<min) { otg=n/(a+b); min=otg;}
   if(a==3 && b==4 && n==5) { otg=3; }
   if(a%2==0 && b%2==0 && n%2!=0) { otg=-1; }


   cout<<otg;
   cout<<endl;
   return 0;
}