#include <bits/stdc++.h>

using namespace std;

const int N = 5e5 + 5;

int n, m;

struct Seg
{
	int cnt, ls[N * 40], rs[N * 40], siz[N * 40];
	void build(int &p, int l, int r)
	{
		p = ++cnt;
		if(l == r) return siz[p] = 1, void();
		int mid = (l + r) >> 1;
		build(ls[p], l, mid), build(rs[p], mid + 1, r);
		siz[p] = siz[ls[p]] + siz[rs[p]];
		return;
	}
	void Copy(int x, int &y, int l, int r, int L, int R)
	{
		if(!x) return;
		if(L <= l && r <= R) return y = x, void();
		int mid = (l + r) >> 1; cnt++;
		ls[cnt] = ls[y], rs[cnt] = rs[y], siz[cnt] = siz[y]; y = cnt;
		if(L <= mid) Copy(ls[x], ls[y], l, mid, L, R);
		if(R > mid) Copy(rs[x], rs[y], mid + 1, r, L, R);
		siz[y] = siz[ls[y]] + siz[rs[y]];
		return;
	}
	int qry(int p, int l, int r, int L, int R)
	{
		if(!p || l > R || r < L) return 0;
		if(L <= l && r <= R) return siz[p];
		int mid = (l + r) >> 1;
		return qry(ls[p], l, mid, L, R) + qry(rs[p], mid + 1, r, L, R);
	}
} T; int rt[N];

int qry(int L, int R, int l, int r)
{
	int ans = 0;
	while(l <= r)
	{
		int mid = (l + r) >> 1;
		if(T.qry(rt[mid], 1, n, L, R)) l = mid + 1, ans = mid;
		else r = mid - 1;
	}
	return ans;
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr), cout.tie(nullptr);

	cin >> n >> m;
	T.build(rt[0], 1, n);
	for(int i = 1; i <= m; i++)
	{
		int op, l, r, x; cin >> op >> l >> r;
		if(op == 1) cin >> x, T.Copy(rt[x], rt[x + 1], 1, n, l, r);
		else cout << qry(l, r, 0, i) << '\n';
	}
	cerr << 1.0 * clock() / CLOCKS_PER_SEC << '\n';
	return 0;
}