#include <iostream>
#include <vector>
#include <queue>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <algorithm>
#define int long long
#define inf 2e18

using namespace std;
const int N = 1e6 + 10;
typedef long long ll;

inline char gc()
{
  return getchar();
}
inline void pc(char c)
{
  putchar(c);
}
ll readin()
{
  ll x = 0;
  int opt = 1;
  char c = gc();
  while (c < '0' || c > '9')
  {
    if (c == '-')
      opt = -1;
    c = gc();
  }
  while (c >= '0' && c <= '9')
  {
    x = x * 10 + (c - '0');
    c = gc();
  }
  return opt * x;
}
inline ll ls(ll x)
{
  return x << 1;
}
inline ll rs(ll x)
{
  return x << 1 | 1;
}

ll a[N << 2];
ll mx[N << 2];
ll tag[N << 2];
ll tot[N << 2];

void push_up(int x)
{
  mx[x] = max(mx[ls(x)], mx[rs(x)]);
}
void build(int x, int l, int r)
{
  if (l == r)
  {
    tot[x] = -inf;
    mx[x] = a[l];
    return ;
  }
  int mid = (l + r) >> 1;
  build(ls(x), l, mid);
  build(rs(x), mid + 1, r);
  push_up(x);
}
void add(int x, int l, int r, ll k)
{
  mx[x] += k;
  tag[x] += k;
}
void gai(int x, int l, int r, ll k)
{
  mx[x] = k;
  tot[x] = k;
  tag[x] = 0;
}
void push_down_tot(int x, int l, int r)
{
  if (tot[x] != -inf)
  {
    int mid = (l + r) >> 1;
    gai(ls(x), l, mid, tot[x]);
    gai(rs(x), mid + 1, r, tot[x]);
    tot[x] = -inf;
  }
}
void push_down_tag(int x, int l, int r)
{
  if (tag[x] != 0)
  {
    push_down_tot(x, l, r);
    int mid = (l + r) >> 1;
    add(ls(x), l, mid, tag[x]);
    add(rs(x), mid + 1, r, tag[x]);
    tag[x] = 0;
  }
}
void add_lr(int x, int l, int r, int L, int R, ll k)
{
  if (L <= l && r <= R)
  {
    push_down_tot(x, l, r);
    add(x, l, r, k);
    return ;
  }
  int mid = (l + r) >> 1;
  push_down_tot(x, l, r);
  push_down_tag(x, l, r);
  if (L <= mid)
    add_lr(ls(x), l, mid, L, R, k);
  if (R > mid)
    add_lr(rs(x), mid + 1, r, L, R, k);
  push_up(x);
}
void gai_lr(int x, int l, int r, int L, int R, ll k)
{
  if (L <= r && r <= R)
  {
    gai(x, l, r, k);
    return ;
  }
  int mid = (l + r) >> 1;
  push_down_tot(x, l, r);
  push_down_tag(x, l, r);
  if (L <= mid)
    gai_lr(ls(x), l, mid, L, R, k);
  if (R > mid)
    gai_lr(rs(x), mid + 1, r, L, R, k);
  push_up(x);
}
ll query(int x, int l, int r, int L, int R)
{
  if (L <= l && r <= R)
    return mx[x];
  int mid = (l + r) >> 1;
  push_down_tot(x, l, r);
  push_down_tag(x, l, r);
  ll ret = -2e18;
  if (L <= mid)
    ret = max(ret, query(ls(x), l, mid, L, R));
  if (R > mid)
    ret = max(ret, query(rs(x), mid + 1, r, L, R));
  return ret;
}

signed main()
{
  int n, q;
  n = readin();
  q = readin();
  for (int i = 1; i <= n; ++i)
    a[i] = readin();
  build(1, 1, n);
  for (int i = 1; i <= 4 * n; ++i)
    tot[i] = -inf;
  while (q--)
  {
    int opt, l, r;
    opt = readin();
    l = readin();
    r = readin();
    if (opt == 1)
    {
      ll x;
      x = readin();
      gai_lr(1, 1, n, l, r, x);
    }
    if (opt == 2)
    {
      ll x;
      x = readin();
      add_lr(1, 1, n, l, r, x);
    }
    if (opt == 3)
    {
      cout << query(1, 1, n, l, r);
      pc('\n');
    }
  }
  return 0;
}