#include<stdio.h>
int p,n;
void citire(){
   freopen("fact.in","r",stdin);
   scanf("%d",&p);
}
int rezolvare(){
     int k=1,put=0;
     if(p==0)
       return 1;
     int aux=p;
     while(aux>5){
       aux/=5;
       put++;
     }
     for(int i=1;i<=put;i++){
        p-=k;
        k*=5;
     }
     return p*5;
}
void afisare(){
     freopen("fact.out","w",stdout);
     printf("%d",rezolvare());
     fclose(stdout);
}
int main(){
    citire();
    afisare();
    return 0;
}