/**
 * user: caen1
 * file: infoarena/fact.c
 * date: 23 apr 2011
**/
#include <stdio.h>

#define IN "fact.in"
#define OUT "fact.out"

int main(void) {

    long p;
    long long n, c_n, i = 1;

    (void) freopen(IN, "r", stdin);
    (void) freopen(OUT, "w", stdout);

    (void) scanf("%ld", &p);

    for(n = 5; i < p; n += 5) {

        c_n = n; while(!(c_n % 5)) ++i, c_n /= 5;
    }

    printf("%lld\n", n);

    return 0;
}