#include <stdio.h>
#include <stdlib.h>
int nrzero(int n){
  int nr=0;
  while(n>=5){
    nr+=n/5;
    n/=5;
  }
  return nr;
}
int caut(int p){
  int r=0, pas=1<<28;
  while(pas!=0){
    if(nrzero(r+pas)<p)
      r+=pas;
    pas/=2;
  }
  r++;
  return r;
}
int main(){
    FILE *fin, *fout;
    int p, x;
    fin=fopen("fact.in", "r");
    fscanf(fin, "%d", &p);
    fclose(fin);
    x=caut(p);
    fout=fopen("fact.out", "w");
    if(nrzero(x)!=p)
      fprintf(fout, "-1");
    else
      fprintf(fout, "%d", x);
    fclose(fout);
    return 0;
}