/*
TASK: minjumps
LANG: C++
*/
#include <iostream>
#include <math.h>
#include <limits.h>
using namespace std;

int n, a, b;
int s = INT_MAX;
bool f = 0;

int main()
{
    cin>>a>>b>>n;
    if(n<0) n*=-1;
    if(n==0) {cout<<"0"<<'\n'; return 0;}
    for(int k=-(100/a); k<=ceil((b*s+n)/(a*1.0)); k++)
    {
            if((k*a-n)%b) continue;
            f=1;
            s = min(s, abs(k)+abs((a*k-n)/b));
    }
    if(f==0) {cout<<"-1\n"; return 0;}
    cout<<s<<'\n';
    return 0;
}
