#include <iostream>
#include <cstdio>

using namespace std;
int p;
int zero(long long v)
{
    int z=0;
    while(v!=0)
    {
        z+=(v/5);
        v/=5;
    }
    return z;
}
int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    scanf("%d", &p);
    long long pas=1073741824;
    int n=0;
    while(pas!=0)
    {
        if(zero(n+pas)<p)
            n+=pas;
        pas/=2;
    }
    if(zero(n+1)!=p)
        cout<<"-1";
    else
        cout<<n+1;
    return 0;
}