#include <vector>
#include <set>
#include <iostream>

using namespace std;
const int inf = 1e9-5;
struct X {
	set<int> vals;
};

int closest(int x, set<int> &a) {
	auto u = a.upper_bound(x);
	auto l = a.lower_bound(x);
	int ans = -inf;
	if (u != a.begin()) 
		ans = *prev(u);
	if (l != a.end()) 
		if (abs(ans-x) > abs(*l-x)) ans = *l;
	return ans;
}

int closest(int x, int y, int z) {
	if (abs(x-y) < abs(x-z)) return y;
	else return z;
}

struct Segtree {
	int n;
	vector<set<int>> tree;
	Segtree(int n): n(n), tree(2*n) {
	}

	void insert(int idx, int val) {
		idx += n;
		while (idx > 0) {
			tree[idx].insert(val);
			idx /= 2;
		}
	}

	int act(int l, int r, int targ) {
		int out = -inf;
		for (l+=n,r+=n; l < r; l /= 2, r /= 2) {
			if ((l&1)) {
				out = closest(targ, out, closest(targ, tree[l]));
				l++;
			}
			if (r&1) {
				r--;
				out = closest(targ, out, closest(targ, tree[r]));
			}
		}
		return out;
	}
};

void solve() {
	int n, m; cin >> n >> m;
	Segtree s(n);
	for (int i = 0; i < m; i++) {
		int type; cin >> type;
		if (type == 0) {
			int x, h; cin >> x>> h;
			s.insert(x-1, h);
		}
		else {
			int l, r, h; cin >> l >> r >> h;
			l--;
			int ans = s.act(l, r, h);
			if (ans == -inf) cout << -1 << '\n';
			else cout << abs(ans-h) << '\n';
		}
	}

}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	int t; cin >> t;
	while (t--) solve();

}