f[i][j]的含义是在第i个月，在幸福度为j的情况下，能有的最多的钱。

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

const int N = 1e5 + 10;
int f[52][N];
void solve() {
    int n, x, c, h;
    cin >> n >> x >> c >> h;
    memset(f + 1, -0x3f, sizeof(f[0]) * n);
    f[1][0] = x;
    int total = 0;
    unordered_set<int> candidate[2];
    candidate[1].insert(0);
    if (c == 0) {
        f[1][total = h] = x;
        candidate[1].insert(h);
    }
    for (int i = 2; i <= n; ++i) {
        cin >> c >> h;
        total += h;
        bool first_enter = true;
        candidate[i & 1] = candidate[i - 1 & 1];
        for (int j : candidate[i - 1 & 1]) {
            f[i][j] = f[i - 1][j] + x;
            if (f[i - 1][j] >= c) {
                f[i][j + h] = max(f[i][j + h], f[i - 1][j] - c + x);
                candidate[i & 1].insert(j + h);
                total = max(total, j + h);
            }
        }
    }
    for (int j = total; j + 1; j--)
        if (f[n][j] >= 0) {
            cout << j << "\n";
            return;
        }
    cout << "0\n";
}
signed main() {
#ifndef ONLINE_JUDGE
    freopen(".in", "r", stdin);
#else
    cin.tie(0)->sync_with_stdio(0);
#endif
    int t;
    cin >> t;
    while (t--)
        solve();
    return 0;
}