#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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