#include <bits/stdc++.h>
using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int INF = 1e9 + 7;

int main()
{
	ios::sync_with_stdio(0); 
	cin.tie(0);
	
	int n, k;
	cin >> n >> k;
	
	LL A = 0;
	VI a(n);
	FOR(i, 0, n)
	{
		cin >> a[i];
		A += a[i];
	}
	
	VI cnt(n);
	FOR(i, 0, k)
	{
		int x;
		cin >> x;
		cnt[x - 1]++;
	}
	VI when(n);
	FOR(i, 0, n)
	{
		//(cnt[i] + 1) * A / a[i] <= N
		when[i] = ((cnt[i] + 1) * A + a[i] - 1) / a[i];	
	}
	sort(ALL(when));
	int sz = k;
	FOR(i, 0, n)
	{
		if(when[i] <= sz)
		{
			cout << i - 1 << "\n";
			return 0;
		}
		sz++;
	}
	cout << "forever\n";


	
	return 0;
}