#include<stdio.h>

long nrzero(long n){
     long nr=0;
     while(n>1){
         nr+=n/5; 
         n=n/5;
     }
     return nr;
}

long p;
long factorial(long l, long r){
     long m=(l+r)/2;
     long nm=nrzero(m);
    
     if(nm==p)
         return m;
     if(nm>p)
         return factorial(l,m-1);
     return factorial(m+1, r);    
}         


int main(){
    FILE *f=fopen("fact.in","r");
    FILE *g=fopen("fact.out","w");
    fscanf(f,"%ld",&p);
 
    if(p==0)
        fprintf(g,"%ld",1);
    else    
       fprintf(g,"%ld",factorial(1,10000000)/5*5); 
   
    fclose(f);
    fclose(g);   
    return 0;
}