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A.cpp
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A.cpp
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#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <iomanip>
#include <list>
#include <map>
#include <iostream>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <unordered_map>
#include <unordered_set>
#define x first
#define y second
#define mp make_pair
#define pb push_back
#define em emplace_back
#define sqr(x) (x) * (x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
const int INF = 2E9 + 3;
int main() {
ios_base::sync_with_stdio(0);
int t;
cin >> t;
while (t--) {
int n, x;
cin >> n >> x;
int dh = -INF, dm = -INF;
for (int i = 0; i < n; ++i) {
int d, h;
cin >> d >> h;
dh = max(dh, d - h);
dm = max(d, dm);
}
if (x <= dm) {
cout << "1\n";
continue;
}
if (dh <= 0) {
cout << "-1\n";
continue;
}
cout << (x - dm - 1) / dh + 2 << '\n';
}
}