#include <iostream>
#include <fstream>
using namespace std;
ifstream h("fact.in");
ofstream g("fact.out");
int cinci(int x ){
int s,r,m,n;
s=x/5;
r=x/25;
m=x/125;
n=s+r+m;
return n;
}
int cautarebin(int x){
int hi=10000 , lo=1,mid;
while(hi-lo>1){
    mid=(lo+hi)/2;
    if(cinci(mid)<x)
        lo=mid;
    else
        hi=mid;
    }


return hi;

}

int main()
{int x,m,n,mij;
h>>x;
if(x==1)g<<"10";
else if(x==0)g<<"1";
 else g<<cautarebin(x);

    return 0;
}