#include <bits/stdc++.h>

struct Node;

struct Ptr {
    uint32_t x;
    Ptr(uint32_t x = 0) : x(x) {}
    Ptr(Node *u);
    explicit operator bool() { return x; }
    Node *operator->();
    Node &operator*();
};

struct Node { Ptr l, r; };

const int N = 30000005;

uint32_t cnt = 0;
Node pool[N];
Node *Ptr::operator->() { return pool + x; }
Node &Ptr::operator*() { return pool[x]; }
Ptr::Ptr(Node *u) { x = u - pool; }

Ptr new_node() { return ++cnt; }
Ptr new_node(Ptr x) { return *Ptr(++cnt) = *x, cnt; }

void build(Ptr u, int l, int r) {
    if (l == r) return;
    int mid = l + r >> 1;
    build(u->l = new_node(), l, mid);
    build(u->r = new_node(), mid + 1, r);
}

void merge(Ptr &u, Ptr v, int l, int r, int L, int R) {
    if (!v) return;
    if (l >= L && r <= R) return u = v, void(0);
    int mid = l + r >> 1;
    u = new_node(u);
    if (L <= mid) merge(u->l, v->l, l, mid, L, R);
    if (R > mid) merge(u->r, v->r, mid + 1, r, L, R);
    if (!u->l && !u->r) u = 0u;
}

bool find(Ptr u, int l, int r, int L, int R) {
    if (!u) return false;
    if (l >= L && r <= R) return true;
    int mid = l + r >> 1;
    if (L <= mid && find(u->l, l, mid, L, R)) return true;
    if (R > mid && find(u->r, mid + 1, r, L, R)) return true;
    return false;
}

int main() {
    // freopen("debt.in", "r", stdin);
    // freopen("debt.out", "w", stdout);

    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr), std::cout.tie(nullptr);
    
    int n, q;
    std::cin >> n >> q;

    std::vector<Ptr> a(q + 1);
    build(a[0] = new_node(), 1, n);
    
    while (q--) {
        int op;
        std::cin >> op;
        if (op == 1) {
            int l, r, x;
            std::cin >> l >> r >> x;
            if (x + 1 < a.size()) merge(a[x + 1], a[x], 1, n, l, r);
        } else {
            int L, R;
            std::cin >> L >> R;
            
            int l = 0, r = a.size();
            while (l + 1 < r) {
                int mid = l + r >> 1;
                (find(a[mid], 1, n, L, R) ? l : r) = mid;
            }
            std::cout << l << '\n';
        }
    }

    return 0;
}