#include <bits/stdc++.h>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
unsigned long long n,i,r,li,ls,z,m,nrzero,NR;
long long cb(unsigned long long x, unsigned long long y)
{
    unsigned long long af;
    af = 0;
    li = x;
    ls = y;
    while(li <= ls)
    {
        m = (li+ls)/2;
        nrzero = 0;
        for(i = 5; i <= m; i *= 5)
            nrzero += m/i;
        if(nrzero == n)
            af = m;
        if(nrzero < n)
            li = m+1;
        else
            ls = m-1;
    }
    if(af == 0)
        return -1;
    else
        return af;
}
int main()
{
    fin >> n;
    fout << cb(1,ULLONG_MAX-10);
}