#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *r, *w;
    r = fopen("fact.in", "r");
    w = fopen("fact.out", "w");

    int p, start = 0, cstart;
    fscanf(r, "%d%d", &p);

    if(p == 0){
        fprintf(w, "1");
        return 0;
    }

    while(p > 0){
        start += 5;
        cstart = start;
        while(cstart%5 == 0){
            cstart /= 5;
            p--;
        }
    }

    if(p == 0){
        fprintf(w, "%d", start);
        return 0;
    }

    fprintf(w, "-1");
    return 0;
}