699C - Vacations - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n;cin>>n;
	int ans=0;
	vector<int>v(n);
	for(int i=0;i<n;i++){
		cin>>v[i];
		if(i){
			if(v[i]==v[i-1] && v[i-1]!=3)v[i]=0;
			if(v[i]==3 && v[i-1]!=3)v[i]=v[i]-v[i-1];
		}
		if(!v[i])
		    ans++;
	}
	cout<<ans;
	return 0;
}