#include <stdio.h>
FILE *fin , *fout;
int func (long long nr)
{
    int suma = 0;
    while(nr>0)
    {
        suma=suma+(nr/5);
        nr/=5;
    }
    return suma;
}

int main()
{
    int n;
    fin = fopen ("fact.in" ,"r");
    fout = fopen ("fact.out" ,"w");
    fscanf(fin ,"%d" ,&n);
    long long  i=1;
    long long ver;
    int ok=1;
    while(ok==1)
    {
        ver = func(i);
        if(n==ver)
        {
            ok=0;
            fprintf(fout ,"%d" ,i);
        }
        i++;
    }
    return 0;
}