/*
   Username : moondancer
   Name : Moon Dancer
*/


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

#define int long long

signed main(){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n;
    cin>>n;
    int l=1,r=2e18;
    int ans=0;
    while(l<=r){
        int mid=(l+r)/2;
        int x=mid;
        int s=0;
        while(x){
            s+=x/5;
            x/=5;
        }
        if(s>=n){
            ans=mid;
            r=mid-1;
        }
        else{
            l=mid+1;
        }
    }
    int t=0;
    int xx=ans;
    while(ans){
        t+=ans/5;
        ans/=5;
    }
    if(t==n) cout<<xx;
    else cout<<-1;
    return 0;
}