#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ii pair<int,int>
#define iii pair<int, ii>
#define fi first
#define se second
#define inf 10000000000000000
const int N = 2005;
int n, h[N], l[N], d, b[N], vis[N];
int ans = 0;
void bt(int pos, int n) {
    if(pos > n) {
        int sum = 0, cnt = 0;
        for(int j = 1; j <= n; j++) {
            int vt = b[j];
            sum += h[vt];
        }
        for(int i = n; i >= 1; i--) {
            int vt = b[i];
            if(sum + l[vt] >= d) {
                cnt++;
                sum -= h[vt];
            }
        }
        ans = max(ans,cnt);
        return;
    }
    for(int j = 1; j <= n; j++) {
        if(vis[j] == 0) {
            b[pos] = j;
            vis[j] = 1;
            bt(pos+1,n);
            vis[j] = 0;
        }
    }
}
signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
 
        freopen("code.inp", "r", stdin);
        freopen("code.ans", "w", stdout);
 
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> h[i] >> l[i];
    cin >> d;
    bt(1,n);
    cout << ans;
    return 0;
}
 
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