#include <bits/stdc++.h>
using namespace std;
long long spf[101];
long long fac[101];
void sieve() {
  spf[1] = 1;
  for (long long i = 2; i < 101; i++) spf[i] = i;
  for (long long i = 4; i < 101; i += 2) spf[i] = 2;
  for (long long i = 3; i * i < 101; i++) {
    if (spf[i] == i) {
      for (long long j = i * i; j < 101; j += i)
        if (spf[j] == j) spf[j] = i;
    }
  }
}
map<long long, long long> getfactor(long long a) {
  map<long long, long long> m;
  while (a > 1) {
    m[spf[a]]++;
    a /= spf[a];
  }
  return m;
}
long long power(long long x, long long y, long long p) {
  long long res = 1;
  x = x;
  if (x == 0) return 0;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long gcd(long long a, long long b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long inverse(long long a, long long p) { return power(a, p - 2, p); }
long long ncr(long long n, long long r, long long p) {
  if (r == 0) return 1;
  return (fac[n] * inverse(fac[r], p) % p * inverse(fac[n - r], p) % p) % p;
}
long long pre1[200000] = {0}, pre2[200000] = {0};
void solve() {
  long long n;
  cin >> n;
  for (long long i = 1; i <= n; i++) {
    long long x;
    cin >> x;
    pre1[i] += pre1[i - 1] + (x == 1);
    pre2[i] += pre2[i - 1] + (x == 2);
  }
  for (long long i = n + 1; i <= 150000; i++) {
    pre1[i] += pre1[i - 1] + 1;
    pre2[i] += pre2[i - 1] + 1;
  }
  vector<pair<long long, long long> > v;
  for (long long i = 1; i <= n; i++) {
    long long j = 0;
    long long count1 = 0, count2 = 0;
    long long counter = 0;
    while (1) {
      long long g = lower_bound(pre1 + j, pre1 + 140000, pre1[j] + i) - pre1;
      long long l = lower_bound(pre2 + j, pre2 + 140000, pre2[j] + i) - pre2;
      if (g == n && l > n) {
        count1++;
        if (count1 > count2) {
          v.push_back(make_pair(count1, i));
          break;
        }
      }
      if (l == n && g > n) {
        count2++;
        if (count2 > count1) {
          v.push_back(make_pair(count2, i));
          break;
        }
      }
      if (l > n && g > n) break;
      if (l < g) {
        count2++;
        j = l;
      } else {
        count1++;
        j = g;
      }
    }
  }
  sort(v.begin(), v.end());
  cout << v.size() << '\n';
  for (auto it : v) cout << it.first << " " << it.second << '\n';
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long t = 1;
  while (t--) {
    solve();
  }
}
