#include <fstream>
#include <stdio.h>
using namespace std;
FILE * f;
long long p,i,div,nr;
int main()
{
    f=fopen("factorial.in","r");
    ofstream fout("factorial.out");
    fscanf(f,"%d",&p);
    if(p==0)fout<<1;
    else{
    for(i=5;div<=p;i+=5){
nr=i;
while(nr%5==0) {div++;nr=nr/5;}
}}

fout<<i-10;
    fclose(f);
    fout.close();
    return 0;
}