Codeforces Round #363 (Div. 1) A. Vacations（dp）

A. Vacations

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Vasya has n days of vacations! So he decided to improve his IT skills and do sport. Vasya knows the following information about each of this n days: whether that gym opened and whether a contest was carried out in the Internet on that day. For the i-th day there are four options:

1. on this day the gym is closed and the contest is not carried out;
2. on this day the gym is closed and the contest is carried out;
3. on this day the gym is open and the contest is not carried out;
4. on this day the gym is open and the contest is carried out.

On each of days Vasya can either have a rest or write the contest (if it is carried out on this day), or do sport (if the gym is open on this day).

Find the minimum number of days on which Vasya will have a rest (it means, he will not do sport and write the contest at the same time). The only limitation that Vasya has — he does not want to do the same activity on two consecutive days: it means, he will not do sport on two consecutive days, and write the contest on two consecutive days.

Input

The first line contains a positive integer n (1 ≤ n ≤ 100) — the number of days of Vasya's vacations.

The second line contains the sequence of integers a1, a2, ..., an (0 ≤ ai ≤ 3) separated by space, where:

• ai equals 0, if on the i-th day of vacations the gym is closed and the contest is not carried out;
• ai equals 1, if on the i-th day of vacations the gym is closed, but the contest is carried out;
• ai equals 2, if on the i-th day of vacations the gym is open and the contest is not carried out;
• ai equals 3, if on the i-th day of vacations the gym is open and the contest is carried out.

Output

Print the minimum possible number of days on which Vasya will have a rest. Remember that Vasya refuses:

• to do sport on any two consecutive days,
• to write the contest on any two consecutive days.

Examples

input

4
1 3 2 0

output

2

input

7
1 3 3 2 1 2 3

output

0

input

2
2 2

output

1

Note

In the first test Vasya can write the contest on the day number 1 and do sport on the day number 3. Thus, he will have a rest for only 2 days.

In the second test Vasya should write contests on days number 1, 3, 5 and 7, in other days do sport. Thus, he will not have a rest for a single day.

In the third test Vasya can do sport either on a day number 1 or number 2. He can not do sport in two days, because it will be contrary to the his limitation. Thus, he will have a rest for only one day.

题解：dp题。

设dp[i][0]表示前i天中去打比赛而没得休息的天数。

dp[i][1]表示前i天中去打运动而没得休息的天数。

dp[i][2]表示前i天中去运动和打比赛而没得休息的天数。

AC代码：

#pragma comment(linker, "/STACK:102400000,102400000")
//#include<bits/stdc++.h>
#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<vector>
#include<map>
#include<cmath>
#include<queue>
#include<set>
#include <utility>
#include<stack>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define mst(a) memset(a, 0, sizeof(a))
#define M_P(x,y) make_pair(x,y)  
#define rep(i,j,k) for (int i = j; i <= k; i++)  
#define per(i,j,k) for (int i = j; i >= k; i--)  
#define lson x << 1, l, mid  
#define rson x << 1 | 1, mid + 1, r  
const int lowbit(int x) { return x&-x; }  
const double eps = 1e-8;  
const int INF = 1e9+7; 
const ll inf =(1LL<<62) ;
const int MOD = 1e9 + 7;  
const ll mod = (1LL<<32);
const int N = 1010;
const int M=100010; 
template <class T1, class T2>inline void getmax(T1 &a, T2 b) {if(b>a)a = b;}  
template <class T1, class T2>inline void getmin(T1 &a, T2 b) {if(b<a)a = b;}
int read()
{
	int v = 0, f = 1;
	char c =getchar();
	while( c < 48 || 57 < c ){
		if(c=='-') f = -1;
		c = getchar();
	}
	while(48 <= c && c <= 57) 
		v = v*10+c-48, c = getchar();
	return v*f;
}
int dp[110][3];
int n;
int main() 
{
    #ifndef ONLINE_JUDGE
    freopen("in.txt","r",stdin);
    #endif
	cin>>n;
	int x;
	for (int i=1;i<=n;i++)
	{
		cin>>x;
		dp[i][0]=max(dp[i-1][0],max(dp[i-1][1],dp[i-1][2]));
		if (x==1 || x==3) dp[i][1]=max(dp[i-1][0],dp[i-1][2])+1;
		if (x==2 || x==3) dp[i][2]=max(dp[i-1][0],dp[i-1][1])+1;
	}	
	cout<<n-max(dp[n][0],max(dp[n][1],dp[n][2]));
	return 0; 
}