#include<fstream.h>
int desc(long long n){
     int p=0;
     while(n%5==0){
        n=n/5;
        p++;
     }
     return p;
}
int main(){
     long x=5,p;
     ifstream f("fact.in");
     ofstream g("fact.out");
     f>>p;
     if(p==0) g<<1<<"\n";
     else{
     while(p>0){
         p-=desc(x);
         x+=5;
     }
     g<<x-5;
     }
     g.close();
     return 0;
}