#include <stdio.h>
int main(){
    long long st = 0, dr = 500000000, mijl, p, aux,nz;
    FILE* in  = fopen("fact.in", "r");
    FILE*out  = fopen("fact.out","w");

    fscanf(in,"%lld",&p);
    while (st<dr){
	  mijl = (st+dr)/2;
	  if (mijl%10 >= 5){
	     mijl /=10;
	     mijl = mijl * 10 +5;
	  }else{
	     mijl /=10;
	     mijl *=10;
	  }
	  if (aux == mijl) break;
	  else {
	     aux  = mijl;
	     nz   = 0;
	     while (aux){
		   nz+= aux/5;
		   aux/=5;
	     }
	     if (nz>p)
		dr = mijl-1;
	     if (nz<p)
		st = mijl + 1;
	     if (nz == p) break;
	     aux = mijl;
	  }
    }
    if (nz == p) fprintf(out, "%lld", mijl);
    else fprintf(out, "-1");
    return 0;
}