#include <iostream>
#include <cstdio>
using namespace std;

int a[100000000];
long long int p;

int zero(long long int x)
{
    long long int s = 0;
    while(x>5)
    {
        s+=x/5;
        x/=5;
    }
    return s;
}

void rez(long long int lg)
{
    long long i;
    for(i = 100000000; lg; lg>>=1)
        if(i-lg>0 && zero(i-lg) >= p)
            i-=lg;
    printf("%d \n", i);
}

int main()
{
    long long int lg = 134217728;
    freopen("fact.in", "r", stdin);
    freopen("fact.out", "w", stdout);
    scanf("%d", &p);
    rez(lg);
    return 0;
}