#include <iostream>
using namespace std;
typedef long long ll;
ll a,b,c;
ll gcd(ll n,ll m){
    if(m==0)return n;
    return gcd(m,n%m);
}
int main(void){
    cin>>a>>b>>c;
    if(a+b<c){
        cout<<0<<endl;
        return 0;
    }
    else if(c==0){
        cout<<1<<endl;
        return 0;
    }
    else if(c==a+b){
        cout<<1<<endl;
        return 0;
    }
    else if(a>=c&&b>=c){
        cout<<gcd(c,c)+1LL<<endl;
    }
    else if(b<c&&a<c){
        cout<<gcd(a+b-c,a+b-c)+1LL<<endl;
    }
    else {
        cout<<gcd(min(a,b),min(a,b))+1LL<<endl;
    }
}