#include <iostream>
#include <stdio.h>
#include <math.h>

using namespace std;

int nr_zero(long long x)
{
    int sum = 0;
    for (int i=5;x / i != 0;i*=5)
    {
        sum += x / i;
    }
    return sum;
}

int main()
{
    FILE *input = fopen("fact.in","r");
    FILE *output = fopen("fact.out","w");
    long long p;
    fscanf(input,"%lld",&p);
    long long MAX = pow(10,9);
    long long min = MAX;
    long long right =MAX;
    long long left = 1;
    while (left <= right)
    {
        long long m = (left + right) / 2;
        if (nr_zero(m) == p)
        {
            if (m< min) min = m;
            right = m-1;
        }
        if (nr_zero(m) <  p)
        {
            left = m+1;
        }
        if (nr_zero(m) > p )
        {
            right = m-1;
        }

    }
    fprintf(output,"%lld",min);
    fclose(input);
    fclose(output);
    return 0;
}