/* ***********************************************Author        :ltwyCreated Time  :2014年12月18日 星期四 16时28分12秒File Name     :1.cpp************************************************ */#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <stack>#include <set>#include <map>#include <string>#include <math.h>#include <stdlib.h>#include <time.h>using namespace std;int n;int a[101000];int sum1[101000];int sum2[101000];pair<int, int> p[100100];int get_next(int s, int st, int ed){    if(sum1[ed] - sum1[st-1] <s && sum2[ed] - sum2[st-1] < s)        return -1;    int l = st, r = ed;    int id = ed;    while(l <= r)    {        int mid = (l+r)>>1;        if(sum1[mid] - sum1[st-1] < s&& sum2[mid] - sum2[st-1] < s)        {            l = mid+1;        }        else        {            id = mid;            r = mid -1;        }    }    return id;}int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);       scanf("%d", &n);    for(int i=1; i<=n; i++)    {        scanf("%d", &a[i]);    }    memset(sum1, 0, sizeof(sum1));    memset(sum2, 0, sizeof(sum2));    int T1 = 0, T2 = 0;    for(int i = 1; i<=n; i++)    {        if(a[i] == 1)            T1++;        if(a[i] == 2)            T2++;        sum1[i] = T1;        sum2[i] = T2;    }        int cnt = 0;    int W1 = 0;    int W2 = 0;    bool flag;    for(int s=1; s<=n; s++)    {        W1 = 0;        W2 = 0;        flag = false;        if(sum1[n] < s && sum2[n] < s)            break;        int pos = 1;        int last = 0;        while(pos <= n)        {            int temp = get_next(s, pos, n);            if(temp == -1)            {                flag = true;                break;            }            if(a[temp] == 1)            {                W1++;                last = 1;            }            else            {                W2++;                last = 2;            }            pos = temp+1;        }        if(flag)            continue;        if(W1 == W2)            continue;        if(W1 > W2&& last == 2)            continue;        if(W2 > W1&& last == 1)            continue;        p[cnt++] = make_pair(max(W1, W2), s);    }        printf("%d\n", cnt);    sort(p, p+cnt);    for(int i=0; i<cnt; i++)        printf("%d %d\n", p[i].first, p[i].second);    return 0;}