#include <stdio.h>
#include <math.h>

int main(){
    unsigned int i,j,count,P,N;
    int ans;
    FILE *in,*out;

    in = fopen("fact.in","r");
    out = fopen("fact.out","w+");
    if(!fscanf(in, "%d\n", &P)) return 1; 
    ans = -1;
    if (P==0) 
        ans = 1;
    else{
        i=0; 
        count=0;
        while (count<P){
          i+=5; j=i;

          while(j){
              if(!(j%5))
                  count++;
                  j/=5;
              
          }
        }
        ans = i;
    }
        fprintf(out,"%d",ans);
    fclose(in);
    fclose(out);

    
    getchar();
    return 0;
}