#include<bits/stdc++.h>

using namespace std;

#define ll long long

#define pb push_back

#define mem(a,b) memset((a),(b),sizeof(a))

#define pii pair<int,int>

#define mp make_pair

const int N=1e5+;

int a[N];

int c1[N]={};

int c2[N]={};

pii ans[N];

int main()

{

    ios::sync_with_stdio(false);

    cin.tie();

    int n;

    cin>>n;

    for(int i=;i<=n;i++)

    {

        cin>>a[i];

        c1[i]=c1[i-];

        c2[i]=c2[i-];

        if(a[i]==)c1[i]++;

        else c2[i]++;

    }

    int s1,s2,last1,last2,c=;

    for(int t=;t<=n;t++)

    {

        s1=s2=last1=last2=;

        while(true)

        {

            int t1=lower_bound(c1+,c1+n+,last1+t)-c1;

            int t2=lower_bound(c2+,c2+n+,last2+t)-c2;

            if(t1>n&&t2>n)break;

            int mn=min(t1,t2);

            if(mn==t1)s1++;

            else s2++;

            if(mn==n)

            {

                if(s2>s1&&a[n]==||s1>s2&&a[n]==)

                {

                    ans[c].first=max(s1,s2);

                    ans[c++].second=t;

                }

                break;

            }

            last1=c1[mn];//上一局的最后得分

            last2=c2[mn];//上一局的最后得分

        }

    }

    cout<<c<<endl;

    sort(ans,ans+c);

    for(int i=;i<c;i++)

    cout<<ans[i].first<<' '<<ans[i].second<<endl;

    return ;

}