#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, t1[5000], t2[5000], t3[5000], x = 0, y = 0, z = 0, w, s;
  scanf("%d", &n);
  int a[n];
  for (i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }
  for (i = 0; i < n; i++) {
    if (a[i] == 1) {
      t1[x] = i + 1;
      x++;
    } else if (a[i] == 2) {
      t2[y] = i + 1;
      y++;
    } else if (a[i] == 3) {
      t3[z] = i + 1;
      z++;
    }
  }
  s = min(x, y);
  w = min(s, z);
  printf("%d\n", w);
  for (x = 0, y = 0, z = 0; x < w, y < w, z < w; x++, y++, z++) {
    printf("%d %d %d\n", t1[x], t2[y], t3[z]);
  }
  return 0;
}
