A. Vacations
time limit per test1 second
memory limit per test256 megabytes
inputstandard input
outputstandard 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:

on this day the gym is closed and the contest is not carried out;
on this day the gym is closed and the contest is carried out;
on this day the gym is open and the contest is not carried out;
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
inputCopy
4
1 3 2 0
outputCopy
2
inputCopy
7
1 3 3 2 1 2 3
outputCopy
0
inputCopy
2
2 2
outputCopy
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.

瓦斯亚有n天假期!所以他决定提高自己的IT技能，做运动。关于这n天中的每一天，瓦斯亚都知道以下信息:健身房是否开门，当天是否在互联网上进行了比赛。第一天有四个选择:

在这一天，体育馆关闭，比赛不进行;

在这一天，体育馆关闭，比赛开始;

在这一天，体育馆开放，比赛不进行;

在这一天，体育馆开放，比赛开始了。

在每一天，瓦西娅可以休息或写比赛(如果是在这一天进行)，或做运动(如果健身房在这一天开放)。

找出Vasya休息的最少天数(这意味着，他不会同时做运动和写比赛)。Vasya唯一的限制是——他不想连续两天做同样的活动:这意味着，他不会连续两天做运动，也不会连续两天写比赛。

输入

第一行包含一个正整数n(1≤n≤100)——Vasya的假期天数。

第二行包含整数a1 a2…， an(0≤ai≤3)由空格分隔，其中:

ai = 0，如果假期第i天健身房关闭，比赛不进行;

ai = 1，如果假期第i天健身房关闭，但比赛仍在进行;

ai = 2，如果假期第i天健身房开放，比赛不进行;

ai = 3，如果在假期的第i天，健身房是开放的，比赛开始。

输出

打印出Vasya休息的最少可能天数。记住，瓦斯亚拒绝:

连续两天进行体育活动，

连续两天写比赛。

#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 5;
int a[maxn], dp[maxn][3]; // 0 休息 1 比赛 2 健身 
int main() {
	int n;
	memset(dp, 64, sizeof(dp));
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	dp[0][0] = 0;
	for (int i = 1; i <= n; i++) {
		if (a[i] == 0) { //只能休息
			dp[i][0] = min(dp[i - 1][0], min(dp[i - 1][1], dp[i - 1][2])) + 1;
		} else if (a[i] == 1) {  //可以比赛，也可以休息
			dp[i][0] = min(dp[i - 1][0], min(dp[i - 1][1], dp[i - 1][2])) + 1;
			dp[i][1] = min(dp[i - 1][0], dp[i - 1][2]);
		} else if (a[i] == 2) { // 可以锻炼，也可以休息
			dp[i][0] = min(dp[i - 1][0], min(dp[i - 1][1], dp[i - 1][2])) + 1;
			dp[i][2] = min(dp[i - 1][0], dp[i - 1][1]);
		} else if (a[i] == 3) { //可以锻炼，比赛， 也可以休息
			dp[i][0] = min(dp[i - 1][0], min(dp[i - 1][1], dp[i - 1][2])) + 1;
			dp[i][1] = min(dp[i - 1][0], dp[i - 1][2]);
			dp[i][2] = min(dp[i - 1][0], dp[i - 1][1]);
		}
	}
	cout << min(dp[n][0], min(dp[n][1], dp[n][2])) << endl;
	return 0;
}