/*
TASK: minjumps
LANG: C++
*/
#include<iostream>
using namespace std;
int a,b,n;
int jumps()
{
 int amax=10000/a,bmax=10000/b;
 for(int i=0;i<=amax;i++)
  for(int j=0;j<=bmax;j++)
  {
   int ai=a*i,bj=b*j;
   if((ai+bj==n) || (ai-bj==n) ||(bj-ai==n) || (-(bj+ai)==n))
     return i+j;
  }
 return -1;
}
int main()
{
    cin>>a>>b>>n;
    if(a>b)
     swap(a,b);
    if(n%2==1&&a%2==0&&b%2==0)
      cout<<"-1"<<endl;
    else
      cout<<jumps()<<endl;       
    return 0;
}
