Example

Input

6 3
1 0 0 1 0 1
1 3 2


Output

1
//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
#include <queue>

using namespace std;

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  int N, M; cin >> N >> M;
  vector<bool> b(N);
  REP(i,N){
	int x; cin >> x;
	b[i] = !!x;
  }

  VI p(M); REP(i,M) cin >> p[i];

  int ans = 123456789;
  REP(x,2){
	int i = 0;
	bool init = !!(x % 2);
	vector<bool> t(N), orig = b;
	REP(k,M){
	  REP(j,p[k])
		t[i++] = init;
	  init = !init;
	}
	if(count(ALL(t), true) != count(ALL(orig), true)) continue;

	int cnt = 0;
	for(int i=0;i<N;++i){
	  if(orig[i] != t[i]){
		int j = i;
		while(orig[j] != t[i]) ++j;
		cnt += j - i;
		for(;j>i;--j){
		  orig[j] = orig[j-1];
		  //orig[i] = t[i];
		}
	  }
	}
	ans = min(ans, cnt);
  }

  cout << ans << endl;
  
  return 0;
}