#include <bits/stdc++.h>
using namespace std;
int n;
int num[100008];
int cnt1[100008];
int cnt2[100008];
int cnt;
struct node {
  int s, t;
} ans[100008];
bool cmp(node a, node b) {
  if (a.s == b.s) return a.t < b.t;
  return a.s < b.s;
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &num[i]);
    if (num[i] == 1) {
      cnt1[i] = cnt1[i - 1] + 1;
      cnt2[i] = cnt2[i - 1];
    } else if (num[i] == 2) {
      cnt1[i] = cnt1[i - 1];
      cnt2[i] = cnt2[i - 1] + 1;
    }
  }
  int acnt = 0;
  int bcnt = 0;
  int pre;
  int atmp;
  int btmp;
  for (int i = 1; i <= n; i++) {
    pre = 1;
    acnt = 0;
    bcnt = 0;
    while (true) {
      atmp = lower_bound(cnt1 + pre, cnt1 + 1 + n, i + cnt1[pre - 1]) - cnt1;
      btmp = lower_bound(cnt2 + pre, cnt2 + 1 + n, i + cnt2[pre - 1]) - cnt2;
      if (atmp < btmp) {
        acnt++;
        pre = atmp + 1;
        if (atmp == n) {
          if (num[n] != 2 && acnt > bcnt) {
            cnt++;
            ans[cnt].s = acnt;
            ans[cnt].t = i;
          }
          break;
        }
      } else if (atmp > btmp) {
        bcnt++;
        pre = btmp + 1;
        if (btmp == n) {
          if (num[n] != 1 && acnt < bcnt) {
            cnt++;
            ans[cnt].s = bcnt;
            ans[cnt].t = i;
          }
          break;
        }
      } else {
        break;
      }
    }
  }
  sort(ans + 1, ans + 1 + cnt, cmp);
  printf("%d\n", cnt);
  for (int i = 1; i <= cnt; i++) {
    printf("%d %d\n", ans[i].s, ans[i].t);
  }
  return 0;
}
