#include <iostream>
#include<fstream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");



int main() {
  int a,s=0,x=0;
  in>>a;
    while(s==0){
        if((x/25+x/5)==a){s=x;
        break;}
        x+=5;
    }
    out<<s;
    return 0;
}