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
Input
4 1 3 2 0Output
2Input
7 1 3 3 2 1 2 3Output
0Input
2 2 2Output
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.
题目大意：0表示今天休息，1表示今天做运动，2表示今天比赛，3表示今天比赛或者运动，瓦希斯不想连续两天做同一件事情，给你一个有0123组成的长度为n的序列，计算瓦希斯最少休息天数
Vasya拒绝：
连续两天做运动，
连续两天写比赛。
AC代码：
#include<stdio.h>
int main()
{
int n;
int a[101];
scanf("%d",&n);
for(int i=0;i<n;i++)
scanf("%d",&a[i]);
int ans=0;//记录最少休息天数
if(a[0]==0)
ans++;
for(int i=1;i<n;i++)
{
switch(a[i])
{
case 0:ans++;break;
case 1:
{
if(a[i-1]==1)
ans++,a[i]=0;//如果前一天为 1，这一天也为 1，那么今天只能休息，ans自加 1,将a[i]赋值为0
break;
}
case 2:
{
if(a[i-1]==2)
ans++,a[i]=0;
break;
}
case 3:
{
if(a[i-1]==2)
a[i]=1;//因为是求最少休息天数，如果昨天为 2，那么想要今天不休息，今天就做 1；
if(a[i-1]==1)
a[i]=2;
break;
}
}
}
printf("%d\n",ans);
return 0;
}我平时做题很少用swith语句，今天发现这道题使用switch语句很简单的就做了出来，switch语句也是很强大啊！