#include<bits/stdc++.h>
#define long long int
using namespace std;
const int N = 2e5+10;
int a[N];
int n;
signed main(){
	cin.tie(0);
	cout.tie(0);
	cin >> n;
	int ans = 0;
	int min1=n+1,max1=0,max3=1,min2=n,cnt=0;
	for(int i = 1;i <= n;i ++){
		cin >> a[i];
		if(a[i]==1){
			min1=min(min1,i);
			max1=max(max1,i);
			cnt++;
		}
		if(a[i]==2)min2=min(min2,i);
		if(a[i]==3)max3=max(max3,i);
	}
	ans += cnt;
	for(int i = 1;i < min1;i ++)if(a[i] == 2){ans++;break;}
	for(int i = max1+1;i <= n;i ++)if(a[i] == 3){ans++;break;}
	if(min2>max3&&cnt==0)ans=0;
	cout<<ans<<endl;
	return 0;
}

最后一个点WA，不知道是否缺少特判