#include <algorithm>
#include <cstdio>
#include <vector>
using namespace std;
int read() {
    int v = 0, f = 1;
    char c = getchar();
    while (c < '0' || '9' < c) {
        if (c == '-')
            f = -1;
        c = getchar();
    }
    while ('0' <= c && c <= '9') {
        v = v * 10 + c - '0';
        c = getchar();
    }
    return v * f;
}
const int N = 1e5 + 5;
int n, m, val[N];
struct Node {
    int l, r, ls, rs;
    int v, l0, l1, r0, r1, c0, c1, t;
    void pushup(const Node &x, const Node &y) {
        v = x.v + y.v;
        l0 = x.l0, l1 = x.l1;
        if (x.v == 0)
            l0 = x.r - x.l + 1 + y.l0;
        else if (x.v == x.r - x.l + 1)
            l1 = x.r - x.l + 1 + y.l1;
        r0 = y.r0, r1 = y.r1;
        if (y.v == 0)
            r0 = x.r0 + y.r - y.l + 1;
        else if (y.v == y.r - y.l + 1)
            r1 = x.r1 + y.r - y.l + 1;
        c0 = max(x.r0 + y.l0, max(x.c0, y.c0));
        c1 = max(x.r1 + y.l1, max(x.c1, y.c1));
    }
    void apply(int k) {
        t = k;
        if (k == 0) {
            v = 0;
            l0 = r0 = c0 = r - l + 1;
            l1 = r1 = c1 = 0;
        } else if (k == 1) {
            v = r - l + 1;
            l0 = r0 = c0 = 0;
            l1 = r1 = c1 = r - l + 1;
        } else {
            v = r - l + 1 - v;
            swap(l0, l1);
            swap(r0, r1);
            swap(c0, c1);
        }
    }
};
vector<Node> tr;
int rt;
void pushdown(int p) {
    int &k = tr[p].t;
    if (~k) {
        tr[tr[p].ls].apply(k);
        tr[tr[p].rs].apply(k);
        k = -1;
    }
}
void debug() {
    fprintf(stderr, "==========\n");
    for (int i = 0; i < tr.size(); i++) {
        fprintf(stderr,
                "%d:l=%d,r=%d,ls=%d,rs=%d,v=%d,l0=%d,l1=%d,r0=%d,r1=%d,"
                "c0=%d,c1=%d,t=%d\n",
                i, tr[i].l, tr[i].r, tr[i].ls, tr[i].rs, tr[i].v, tr[i].l0,
                tr[i].l1, tr[i].r0, tr[i].r1, tr[i].c0, tr[i].c1, tr[i].t);
    }
}
int build(int l, int r) {
    int p = tr.size();
    tr.push_back(Node());
    tr[p].l = l, tr[p].r = r, tr[p].t = -1;
    if (l == r) {
        tr[p].v = val[l];
        if (val[l] == 0) {
            tr[p].l0 = tr[p].r0 = tr[p].c0 = 1;
            tr[p].l1 = tr[p].r1 = tr[p].c1 = 0;
        } else {
            tr[p].l0 = tr[p].r0 = tr[p].c0 = 0;
            tr[p].l1 = tr[p].r1 = tr[p].c1 = 1;
        }
        return p;
    }
    int mid = (l + r) >> 1;
    tr[p].ls = build(l, mid);
    tr[p].rs = build(mid + 1, r);
    tr[p].pushup(tr[tr[p].ls], tr[tr[p].rs]);
    return p;
}
void update(int p, int x, int y, int k) {
    int l = tr[p].l, r = tr[p].r;
    // fprintf(stderr, "UPDATE %d %d %d %d %d %d\n", p, l, r, x, y, k);
    if (x <= l && r <= y) {
        tr[p].apply(k);
        return;
    }
    pushdown(p);
    int mid = (l + r) >> 1;
    if (x <= mid)
        update(tr[p].ls, x, y, k);
    if (mid < y)
        update(tr[p].rs, x, y, k);
    tr[p].pushup(tr[tr[p].ls], tr[tr[p].rs]);
}
Node query(int p, int x, int y) {
    int l = tr[p].l, r = tr[p].r;
    // fprintf(stderr, "QUERY %d %d %d %d %d\n", p, l, r, x, y);
    if (x <= l && r <= y)
        return tr[p];
    pushdown(p);
    int mid = (l + r) >> 1;
    Node res;
    if (y <= mid)
        res = query(tr[p].ls, x, y);
    else if (mid < x)
        res = query(tr[p].rs, x, y);
    else
        res.pushup(query(tr[p].ls, x, y), query(tr[p].rs, x, y));
    return res;
}
int main() {
    n = read(), m = read();
    for (int i = 1; i <= n; i++)
        val[i] = read();
    rt = build(1, n);
    // debug();
    for (int i = 1; i <= m; i++) {
        int k = read(), l = read() + 1, r = read() + 1;
        if (1 <= k && k <= 3)
            update(rt, l, r, k);
        else {
            Node p = query(rt, l, r);
            if (k == 3)
                printf("%d\n", p.v);
            else
                printf("%d\n", p.c1);
        }
    }
    return 0;
}

自己条了半天了，发现 build 中似乎返回值有问题。