#include <cstdio>

using namespace std;

int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    int n=0,l=0,nr,p;
    scanf("%d",&p);
    if (p==0)
        printf("%d",1);
    while (l<p)
    {
        n+=5;
        nr=n;
        while(nr%5==0)
        {
        l++;
        if (l==p)
            break;
        nr/=5;
        }
    }
    printf("%d",n);
    return 0;
}