/*
TASK:minjumps
LANG:C++
*/
#include <iostream>
using namespace std;
int main()
{
    int t[2];
    int a,b,n,tmp,q,flag=0,br=0,sum;
    cin >> a >> b >> n;
    if (a>b)
    {
        tmp=a;
        a=b;
        b=tmp;
    }
    if ((n%2==1)&&(a%2==0)&&(b%2==0)) {cout << -1;flag=1;}
    else    if (n%b==0) {cout << (n/b);flag=1;}
    else 
    {
        q=n%b;
        if (q%a==0) {cout << ((n/b)+(q/a));flag=1;}
    }
    if (flag==0)
    {
        q=n%a; 
        if (q%b==0) {cout << ((n/a)+(q/b));flag=1;}
    }
    if (flag==0)
    {
        int z=n/a;
        int x=n/b;
        for (int i=0;i<=z;i++)
            for (int j=0;j<x;j++)
            {sum=j*b+i*a;if (sum==n) {t[0]=j;t[1]=i;flag=1;break;}}
        cout << t[0]+t[1];
    }
    if (flag==0)
    {
        while(n%b!=0)
        {n+=a;br++;}
        cout << ((n/b)+br);
    }
    cout << endl;
return 0;    
}
