UVa 11466

#include<bits/stdc++.h>
using namespace std;

typedef long long int ll;

#define read()             freopen("input.txt", "r", stdin)
#define write()            freopen("output.txt", "w", stdout)

void mxdiv(ll n)
{
    ll x = n, mx = -1, cnt =0;
    if(n%2==0){
        cnt++;
        while(n%2==0){
            n/=2;
        }
    }
    for(ll i=3;i*i<=n;i+=2){
        if(n%i==0){
            cnt++;
            mx = max(mx,i);
            while(n%i==0){
                n/=i;
            }
        }
    }
    if(n>1 && n!=x){
        cnt++;
        mx = max(mx,n);
    }
    if(cnt<=1) mx = -1;
    printf("%lld\n",mx);
}

int main()
{
    //read();
    //write();

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    ll n;
    while(1){
        scanf("%lld",&n);
        if(n==0) break;
        if(n<0) n*=-1;
        mxdiv(n);
    }
    return 0;
}