#include <atcoder/all>
using namespace std;

using S = int;
S e(){return 1;}
S op(S lhs, S rhs){return min(lhs, rhs);}
using F = int;
S mapping(F f, S x){return f == -1 ? x : f;}
F composition(F f, F g){return f == -1 ? g : f;}
F id(){return -1;}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N, Q, type, u, v, L, R;
    cin >> N >> Q;
    vector<int> ca(2 * Q + 1);
    vector<tuple<int, int, int>> query(Q);
    for(int i = 0; i < Q; i++){
        cin >> get<0>(query[i]) >> get<1>(query[i]);
        if(get<0>(query[i]) != 4) cin >> get<2>(query[i]);
        ca[2 * i] = get<1>(query[i]);
        ca[2 * i + 1] = get<2>(query[i]);
    }
    sort(ca.begin(), ca.end());
    ca.erase(unique(ca.begin(), ca.end()), ca.end());
    atcoder::lazy_segtree<S, op, e, F, mapping, composition, id> seg(vector<int>(ca.size(), 0));
    for(int i = 0; i < Q; i++){
        tie(type, u, v) = query[i];
        u = lower_bound(ca.begin(), ca.end(), u) - ca.begin();
        if(v) v = lower_bound(ca.begin(), ca.end(), v) - ca.begin();
        if(type <= 2) seg.apply(u, v, 2 - type);
        else if(type == 3){
            if(u > v) swap(u, v);
            cout << seg.prod(u, v) << '\n';
        }else{
            L = seg.min_left(u, [](int v){return v != 0;} );
            R = seg.max_right(u, [](int v){return v != 0;} );
            cout << ca[R] - ca[L] + 1 << '\n';
        }
    }
}