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

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int INF = 1e9 + 47;

int f(const set<int>& s, int h)
{
	auto it = s.lower_bound(h);
	int res = INF;
	if (it != s.end())
		res = min(res, *it - h);
	if (it != s.begin())
		res = min(res, h - *prev(it));
	return res;
}

struct SegTree
{
	int n;
	vector<set<int>> t;
	void init(int _n)
	{
		n = 1;
		while (n < _n)
			n *= 2;
		t.clear();
		t.resize(2 * n - 1);
	}
	void upd(int v, int tl, int tr, int pos, int h)
	{
		t[v].insert(h);
		if (tl == tr - 1)
		{
			return;
		}
		int tm = (tl + tr) / 2;
		upd(2 * v + 1, tl, tm, pos, h);
		upd(2 * v + 2, tm, tr, pos, h);
	}
	int query(int v, int tl, int tr, int l, int r, int h)
	{
		if (r <= tl || tr <= l)
			return INF;
		if (l <= tl && tr <= r)
			return f(t[v], h);
		int tm = (tl + tr) / 2;
		return min(query(2 * v + 1, tl, tm, l, r, h), query(2 * v + 2, tm, tr, l, r, h));
	}
} st;

void solve()
{
	int n, m;
	cin >> n >> m;
	st.init(n);
	while (m--)
	{
		int t;
		cin >> t;
		if (t == 0)
		{
			int x, h;
			cin >> x >> h;
			x--;
			st.upd(0, 0, st.n, x, h);
		}
		else
		{
			int l, r, h;
			cin >> l >> r >> h;
			l--;
			int ans = st.query(0, 0, st.n, l, r, h);
			cout << (ans == INF ? -1 : ans) << "\n";
		}
	}
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int t;
	cin >> t;
	while (t--)
	{
		solve();
	}
	return 0;
}