#include <cstdio>

using namespace std;

int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);

    int p;
    int z=0;
    int n=0;

    scanf("%d",&p);

    int cn;

    if(p==0)
    {
        printf("1");
        return 0;
    }

    while(z<=p)
    {
        n+=5;
        cn=n;
        while(cn%5==0)
        {
            cn/=5;
            z++;
        }
    }

    printf("%d",n-5);

    return 0;
}