//Shirasu Azusa 2024.7
#include <bits/stdc++.h>
#define fi first
#define se second
#define eb emplace_back
#define mp make_pair
using namespace std;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef __int128 i128;
template<class T,class S>
bool chmax(T &a,const S b) {return (a<b?a=b,1:0);}
template<class T,class S>
bool chmin(T &a,const S b) {return (a>b?a=b,1:0);}
int popcnt(int x) {return __builtin_popcount(x);}
int popcnt(ll x)  {return __builtin_popcountll(x);}
int topbit(int x) {return (x==0?-1:31-__builtin_clz(x));}
int topbit(ll x)  {return (x==0?-1:63-__builtin_clzll(x));}
int lowbit(int x) {return (x==0?-1:__builtin_ctz(x));}
int lowbit(ll x)  {return (x==0?-1:__builtin_ctzll(x));}

#define int long long
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
typedef pair<int,int> pii;  
typedef vector<int> vi;
typedef vector<pii> vp;
typedef tuple<int,int,int> tiii;
int read() {
  int x=0,w=1; char c=getchar();
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+(c-'0'); c=getchar();} 
  return x*w;
}

const int N=5e5+5;
int n,m,a[N];

#define ls (p<<1)
#define rs (p<<1|1)
int f[N<<2];
struct node {int s,h;} tag[N<<2],s[N<<2];
node operator * (node x,node y) {return (node){x.s+y.s,max(x.h,x.s+y.h)};}
node operator + (node x,node y) {return (node){max(x.s,y.s),max(x.h,y.h)};}
void add(int p,node z) {s[p]=s[p]*z, tag[p]=tag[p]*z;}
void psd(int p) {add(ls,tag[p]),add(rs,tag[p]),tag[p]=(node){0,0};}
void psu(int p) {s[p]=s[ls]+s[rs], f[p]=f[ls]&&f[rs]&&(s[ls].s==s[rs].s);}
void add(int p,int l,int r,int x,int y,int z) {
  if(l==x&&r==y) {add(p,(node){z,max(0ll,z)}); return;} int mid=l+r>>1; psd(p);
  if(y<=mid) add(ls,l,mid,x,y,z); else if(x>mid) add(rs,mid+1,r,x,y,z);
  else add(ls,l,mid,x,mid,z), add(rs,mid+1,r,mid+1,y,z); psu(p);
}
void cov(int p,int l,int r,int x,int y,int z) {
  if(l==x&&r==y&&f[p]) {add(p,(node){z-s[p].s,max(0ll,z-s[p].s)}); return;} int mid=l+r>>1; psd(p);
  if(y<=mid) cov(ls,l,mid,x,y,z); else if(x>mid) cov(rs,mid+1,r,x,y,z);
  else cov(ls,l,mid,x,mid,z), cov(rs,mid+1,r,mid+1,y,z); psu(p);
}
node qry(int p,int l,int r,int x,int y) {
  if(l==x&&r==y) return s[p]; int mid=l+r>>1; psd(p);
  if(y<=mid) return qry(ls,l,mid,x,y);
  else if(x>mid) return qry(rs,mid+1,r,x,y);
  else return qry(ls,l,mid,x,mid)+qry(rs,mid+1,r,mid+1,y);
}
void build(int p,int l,int r) {
  if(l==r) {s[p].s=s[p].h=a[l]; f[p]=1; return;} int mid=l+r>>1;
  build(ls,l,mid), build(rs,mid+1,r); psu(p);
}

signed main() {
  n=read(), m=read();
  rep(i,1,n) a[i]=read();
  build(1,1,n);
  rep(i,1,m) {
    int op=read(), l=read(), r=read();
    if(op==1) add(1,1,n,l,r,read());
    else if(op==2) cov(1,1,n,l,r,read());
    else {
      auto [s,h]=qry(1,1,n,l,r);
      if(op==3) printf("%lld\n",s);
      else printf("%lld\n",h);
    }
  }
  return 0;
}