Example

Input

6 3
1 0 0 1 0 1
1 3 2


Output

1
#include <algorithm>
#include <cmath>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <cassert>
#include <functional>

using namespace std;

#define LOG(...) printf(__VA_ARGS__)
//#define LOG(...)
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define RSORT(c) sort((c).rbegin(),(c).rend())
#define CLR(a) memset((a), 0 ,sizeof(a))

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int dx[] = { -1, 0, 1, 0 }; const int dy[] = { 0, 1, 0, -1 };
struct st{
int bit;
int count;
};
int main() {
int n,m;
	cin>>n>>m;
	int bit=0;
	REP(i,n){
	int shift;
	cin >> shift;
	bit |= shift << (n - i-1);
	}
	vector<int> ans(m);
	REP(i,m){
		cin>>ans[i];
	}
	int bit_ans=0;
	int bit_ans2;
	REP(i,m){
		REP(j, ans[i]){
			bit_ans <<=1;
			if (i % 2 == 0){
			bit_ans|=1;
			}
			
	}
	}
	bit_ans2=bit_ans^((1<<n)-1);
	int count=0;
	set<int> dp;
	dp.insert(bit);
	queue<st> P;
	P.push({bit,0});
	while (!P.empty()){
		st p = P.front(); P.pop();
		if (p.bit == bit_ans || p.bit == bit_ans2){
		count=p.count;
		break;
		}
		REP(i,n-1){
			if ((p.bit >> i & 1 ) != (p.bit >> (i + 1) & 1)){
				int bitc = p.bit^3<<i;
				if (dp.find(bitc) == dp.end()){
					dp.insert(bitc);
					P.push({ bitc, p.count + 1 });
				}
			}
		}
	}
	cout<<count<<endl;
}