/* -*- coding: utf-8 -*-
 *
 * 2929.cc:  No.2929 Miracle Branch - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

using ll = long long;
using vi = vector<int>;

/* global variables */

/* subroutines */

/* main */

int main() {
  ll x;
  scanf("%lld", &x);

  vi vs;
  if (x <= 4) vs.push_back(x);
  else {
    for (int i = 2; x > 1 && i <= MAX_N; i++)
      while (x % i == 0)
	vs.push_back(i), x /= i;
    if (x > 1) { puts("-1"); return 0; }
  }

  ll sum = 0;
  for (auto v: vs) sum += v + 1;
  if (sum > MAX_N) { puts("-1"); return 0; }

  int m = vs.size(), n = sum;

  printf("%d\n", n);
  for (int i = 0; i + 1 < m; i++) printf("%d %d\n", i + 1, i + 2);
  for (int i = 0, k = m; i < m; i++)
    for (int j = 0; j < vs[i]; j++)
      printf("%d %d\n", i + 1, (k++) + 1);
  for (int i = 0; i < n; i++)
    printf("%c%c", (i < m) ? 'b' : 'g', (i + 1 < n) ? ' ' : '\n');
  
  return 0;
}