#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<stack>
#include<queue>
#include<cstring>
#include<deque>
#define maxn 30010
using namespace std;
int n,a[maxn],f[maxn],d[maxn],ans=-1,last[5];
//inline void dp(int x,int o);
int in(){
	freopen("egroup.in","r",stdin);
	freopen("egroup.out","w",stdout);
    scanf("%d",&n);
    for (int i=1;i<=n;i++){
    	int x;
    	scanf("%d",&x);
    	for (int j=1;j<=x;j++){
		    if (f[i]<f[last[j]]+1) f[i]=f[last[j]]+1;
	    }
	    ans=max(ans,f[i]);
	    for (int j=x;j<=3;j++){
		    if (d[i]<d[last[j]]+1) d[i]=d[last[j]]+1;
	    }
	    ans=max(ans,d[i]);
	    last[x]=i;
    }
    printf("%d",n-ans);
    return 0;
}
int main(){;}
int xlm=in();