#include <bits/stdc++.h>


using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");

int zeroes(int n){
    int s=0;
    while(n!=0){
        n/=5;
        s+=n;
    }
    return s;
}

int searchP(int p){
    int st=1;
    int dr=INT_MAX-1;
    int mj;
    int nr;
    int res=1;
    while(st<=dr){
        mj=(dr+st)/2;
        nr=zeroes(mj);
//        cout<<st<<" "<<mj<<" "<<dr<<"\n";
        if(nr<p){
            st=mj+1;
        }else{
            dr=mj-1;
            res=mj;
        }
    }
    if(zeroes(res)==p){
            return res;
    }else{
        return -1;
    }

}

int main()
{
    int p;
    in>>p;
    out <<searchP(p);
    return 0;
}