#include <fstream>
#include <iostream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int main(){
    long long p;
    in>>p;
    if(!p){
        out<<1;
    return 0;}
    long long n=0;
    long long p2=0;
    while(p2<p){
        n+=5;
        ++p2;
        if(n%25==0)
            ++p2;
    }
    out<<n;
    return 0;
}