20pts求调（悬三关）

//author : yhy
#include <bits/stdc++.h> 

using namespace std;
using LL = long long;
using PII = pair<LL, LL>;

const LL kMaxN = 1e6 + 5, inf = -1e18;

LL n, q, a[kMaxN];
struct Node {
  LL maxv, add, mdf;
} t[kMaxN << 2];

void push_up(LL cur) {
  t[cur].maxv = max(t[cur * 2].maxv, t[cur * 2 + 1].maxv);
}
void addtag(LL cur, LL x, LL ty) {
  if (ty == 1) {
    t[cur] = {x, 0, x};
  } else {
    t[cur].maxv += x, (t[cur].mdf != inf ? t[cur].mdf += x : t[cur].add += x);
  }
}
void push_down(LL cur) {
  if (!t[cur].add && t[cur].mdf == inf) {
    return;
  }
  addtag(cur * 2, t[cur].mdf, 1), addtag(cur * 2 + 1, t[cur].mdf, 1);
  addtag(cur * 2, t[cur].add, 2), addtag(cur * 2 + 1, t[cur].add, 2);
  t[cur].add = 0, t[cur].mdf = inf;
}
void build (LL cur, LL l, LL r) {
  t[cur].add = 0, t[cur].mdf = inf;
  if (l == r) {
    t[cur].maxv = a[l];
    return;
  }
  LL mid = (l + r) / 2;
  build(cur * 2, l, mid), build(cur * 2 + 1, mid + 1, r);
  push_up(cur);
}
void update(LL cur, LL l, LL r, LL qx, LL qy, LL val, LL ty) {
  if (qx <= l && r <= qy) {
    addtag(cur, val, ty);
    return;
  } if (r < qx || l > qy) {
    return;
  }
  push_down(cur);
  LL mid = (l + r) / 2;
  update(cur * 2, l, mid, qx, qy, val, ty);
  update(cur * 2 + 1, mid + 1, r, qx, qy, val, ty);
  push_up(cur);
}
LL query (LL cur, LL l, LL r, LL qx, LL qy) {
  if (qx <= l && r <= qy) {
    return t[cur].maxv;
  } if (r < qx || l > qy) {
    return -inf;
  }
  push_down(cur);
  LL mid = (l + r) / 2;
  return max(query(cur * 2, l, mid, qx, qy), query(cur * 2 + 1, mid + 1, r, qx, qy));
}

signed main () {
  ios::sync_with_stdio(0), cin.tie(nullptr);
  cin >> n >> q;
  for (LL i = 1; i <= n; i++) {
    cin >> a[i];
  }
  build(1, 1, n);
  for (LL ty, x, y, val; q; q--) {
    cin >> ty >> x >> y;
    if (ty != 3) {
      cin >> val;
      update(1, 1, n, x, y, val, ty);
    } else {
      cout << query(1, 1, n, x, y) << '\n';
    }
  }
  return 0;
}