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

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, b, a) for(int i = (b) - 1; i >= (a); 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;

int main()
{
	ios::sync_with_stdio(0); 
	cin.tie(0);
	cout << fixed << setprecision(15);
	
	int n, k, x;
	cin >> n >> k >> x;
	
	VI t(k + 1), p(k + 1);
	t[0] = 0;
	cin >> p[0];
	
	
	VI s(n);
	FOR(i, 0, n)
		cin >> s[i];
	
	
	FOR(i, 0, k)
		cin >> t[i + 1];
	FOR(i, 0, k)
		cin >> p[i + 1];
	
	int ans = 0;
	set<PII> SS;
	FOR(i, 0, n)
		SS.insert(MP(s[i], i));
	
	FOR(i, 0, k + 1)
	{
		int nS = (x + p[i] - t[i] - 1) / (p[i] - t[i]);
				
		while(SZ(SS) && SS.rbegin()->F >= nS)
		{
			int S = SS.rbegin()->F;
			SS.erase(prev(SS.end()));
			
			
			if((p[k] - t[i]) * S >= x)
				ans++;
		}
	}
	cout << ans << "\n";
	
	
	
	
	return 0;
}