Explain why one test case is showing run time error

question :

kth smallest number again , hacker rank

https://www.hackerearth.com/practice/algorithms/searching/binary-search/practice-problems/algorithm/kth-smallest-number-again-2/

Submission :

Submission:
#include
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define varname(name) #name
#define mod 1000000007
#define wer(x) cout<<"\n"<<varname(x)<<" here : “<<x<<”\n"
#define asdf(a,n) for(int i=0;i<n;i++) cin>>a[i]
#define out(a,n) cout<<"\n"<<varname(a)<<" here is : \n";for(int i=0;i<n;i++) cout<<a[i]<<" "; cout<<endl
#define pb push_back
#define yes cout << “YES” << endl;
#define no cout << “NO” << endl;
#define f first
#define se second

void init()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
#ifndef ONLINE_JUDGE
// for getting input from input.txt
freopen(“input.txt”, “r”, stdin);
// for writing output to output.txt
freopen(“output.txt”, “w”, stdout);
#endif
}

bool compare(pair<int, int> p1 , pair<int, int> p2)
{
if (p1.first <= p2.first)
{
return true;
}
else return false;
}

int lb(int *a, int n, int k)
{
int l = 0;
int h = n - 1;
int ans = -1;
while (l <= h)
{
int m = l + ((h - l) / 2);
if (a[m] >= k)
{
ans = m;
h = m - 1;
}
else
{
l = m + 1;
}
}

return ans;

}

int32_t main()
{
init();
int t = 1;
cin>>t;
while (t–)
{
int n, q;
cin >> n >> q;
vector<pair<int, int> > v;

	for (int i = 0; i < n; i++)
	{
		int a, b;
		cin >> a >> b;

		v.pb({a, b});
	}

	//Convert the given pairs into no-overlapping and sorted pairs

	//sort on the basis of starting point
	sort(v.begin(), v.end() , compare);

	//Merge overlapping sub-intervals

	int starting_point = v[0].f;
	int ending_point = v[0].se;
	int i = 1;

	vector<pair<int, int>> p;

	p.pb({0, 0});

	while (i < n)
	{
		if (v[i].first <= ending_point)
		{
			ending_point = max(ending_point , v[i].se);
			i++;
		}
		else
		{
			p.pb({starting_point, ending_point});
			starting_point = v[i].f;
			ending_point = v[i].se;
			i++;
		}
	}

	p.pb({starting_point, ending_point});

	/*	for (auto x : p)
		{
			cout << x.first << " " << x.second << endl;
		}
	*/



	int w = p.size();

	int *arr = new int[w];


	arr[0] = 0;
	for (int i = 1; i < w; i++)
	{
		arr[i] = arr[i - 1] + (p[i].se - p[i].f + 1);
	}

	//out (arr, w);

	while (q--)
	{
		int k;
		cin >> k;




		if (k > arr[w - 1])
		{
			cout << -1 << endl;
		}
		else
		{
			int idx = lb(arr, w, k);


			cout << (k - arr[idx - 1]) + p[idx].f - 1 << endl;
		}

	}

}
return 0;

}