Codeforces Round #363 (Div. 2) C. Vacations

原题链接

C. 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:

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 0

output

2

input

7
1 3 3 2 1 2 3

output

0

input

22 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.

用dp[i][j]表示在第i天, 生活方式为j时最多忙了多少天

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#define maxn 105
#define INF 1000000000using namespace std;

int dp[maxn][3];
void solve1(int i){

if(dp[i-1][2] != -1)
dp[i][1] = dp[i-1][2] + 1;
dp[i][1] = max(dp[i][1], dp[i-1][0] + 1);
}
void solve2(int i){
if(dp[i-1][1] != -1)
dp[i][2] = dp[i-1][1] + 1;
dp[i][2] = max(dp[i][2], dp[i-1][0] + 1);
}
void solve0(int i){
dp[i][0] = max(max(dp[i-1][1], dp[i-1][2]), dp[i-1][0]);
}
int main(){

// freopen("in.txt", "r", stdin);
int n, a;

scanf("%d", &n);
memset(dp, -1, sizeof(dp));
dp[0][0] = dp[0][1] = dp[0][2] = 0;
for(int i = 1; i <= n; i++){
scanf("%d", &a);
if(a == 1){
solve1(i);
solve0(i);
}
else if(a == 2){
solve2(i);
solve0(i);
}
else if(a == 3){
solve1(i);
solve2(i);
solve0(i);
}
else
solve0(i);
}
printf("%d\n", n - max(max(dp
[0], dp
[1]), dp
[2]));
return 0;
}