#include <iostream>
#include <cstdio>

using namespace std;

int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);

    int i,p,p2,p5,ok,elem,ci;
    cin>>p;
    p2=0;p5=0;
    ok=0;
    elem=-1;
    for(i=1;ok==0;i++){
        ci=i;
        while(ci!=0 && ci%2==0){
            p2++;
            ci=ci/2;
        }
        while(ci!=0 && ci%5==0){
            p5++;
            ci=ci/5;
        }
        if(p5>=p2)
            if(p2==p){
                ok=1;
                elem=i;
            }
        if(p5<p2)
            if(p5==p){
                ok=1;
                elem=i;
            }
    }
    if(p!=0)
        cout<<elem;
    else
        cout<<1;
    return 0;
}