#include <stdio.h>
#include <vector>
#include <algorithm>
using namespace std;

int n;
vector <bool> a;
vector <int> p(0), g(0);
vector <pair <int, int> > res(0);

int main()
{
    scanf("%d", &n);
    a.assign(n, false);
    for (int i = 0; i < n; ++i)
    {
        int x;
        scanf("%d", &x);
        if (x == 2)
        {
            a[x] = true;
            g.push_back(i);
        }
        else
            p.push_back(i);
    }
    p.push_back(n);
    g.push_back(n);

    for (int t = 1; t < n; ++t)
    {
        bool success = true;
        int p_s = 0, g_s = 0, p_i = 0, g_i = 0;
        while (p[p_i] < n || g[g_i] < n)
        {
            if (p_i + t >= p.size())
            {
                if (g_i + t >= g.size())
                {
                    success = false;
                    break;
                }
                g_i += t;
                ++g_s;
                int x = lower_bound(p.begin(), p.end(), g[g_i]) - p.begin();
                --x;
                if (x >= 0 && x < p.size())
                {
                    p_i = max(p_i, x);
                }
                break;
            }

            if (g_i + t >= g.size())
            {
                p_i += t;
                ++p_s;
                int x = lower_bound(g.begin(), g.end(), p[p_i]) - g.begin();
                --x;
                if (x >= 0 && x < g.size())
                {
                    g_i = max(g_i, x);
                }
                break;
            }

            if (p[p_i + t] < g[g_i + t])
            {
                p_i += t;
                ++p_s;
                int x = lower_bound(g.begin(), g.end(), p[p_i]) - g.begin();
                --x;
                if (x >= 0 && x < g.size())
                {
                    g_i = max(g_i, x);
                }
            }
            else
            {
                g_i += t;
                ++g_s;
                int x = lower_bound(p.begin(), p.end(), g[g_i]) - p.begin();
                --x;
                if (x >= 0 && x < p.size())
                {
                    p_i = max(p_i, x);
                }
            }
        }

        if (success && p_s != g_s)
            res.push_back(make_pair(max(p_s, g_s), t));
    }

    sort(res.begin(), res.end());
    printf("%d\n", res.size());
    for (int i = 0; i < res.size(); ++i)
        printf("%d %d\n", res[i].first, res[i].second);

    return 0;
}