#include<bits/stdc++.h>
#define ll long long
using namespace std;
ll n,q;
ll a[1000055];
struct N{
    ll l,r;
    ll maxs,lazy_add,lazy_into;
} tr[4000055];
void push_down(ll c){
    ll lc = 2 * c , rc = 2 * c + 1;
    if(tr[c].lazy_into != -1e18){
        tr[lc].lazy_into = tr[rc].lazy_into = tr[c].lazy_into;
        tr[lc].lazy_add = tr[rc].lazy_add = 0;
        tr[lc].maxs = tr[rc].maxs = tr[c].lazy_into;
        tr[c].lazy_into = -1e18;
    }
    if(tr[c].lazy_add != 0){
        tr[lc].lazy_add += tr[c].lazy_add , tr[rc].lazy_add += tr[c].lazy_add;
        tr[lc].lazy_into = tr[rc].lazy_into = -1e18;
        tr[lc].maxs += tr[c].lazy_add , tr[rc].maxs += tr[c].lazy_add;
        tr[c].lazy_add = 0;
    }
}
void push_up(ll c){
    ll lc = 2 * c , rc = 2 * c + 1;
    tr[c].maxs = max(tr[lc].maxs , tr[rc].maxs);
}
void build(ll c,ll l,ll r){
    tr[c].l = l , tr[c].r = r;
    tr[c].maxs = -1e18;
    tr[c].lazy_into = -1e18;
    if(l == r){
        tr[c].maxs = a[l];
        return ;
    }
    ll mid = (l + r) / 2;
    ll lc = 2 * c , rc = 2 * c + 1;
    build(lc, l, mid);
    build(rc, mid+1, r);
    push_up(c);
}
void update(ll c,ll l,ll r,ll k){
    if(l <= tr[c].l && tr[c].r <= r){
        tr[c].maxs = k;
        tr[c].lazy_into = k;
        tr[c].lazy_add = 0;
        return ;
    }
    push_down(c);
    ll mid = (tr[c].l + tr[c].r) / 2;
    ll lc = 2 * c , rc = 2 * c + 1;
    if(l <= mid) update(lc, l, r, k);
    if(mid+1 <= r) update(rc, l, r, k);
    push_up(c);
}
void add(ll c,ll l,ll r,ll k){
    if(l <= tr[c].l && tr[c].r <= r){
        tr[c].maxs += k;
        tr[c].lazy_add += k;
        tr[c].lazy_into = -1e18;
        return ;
    }
    push_down(c);
    ll mid = (tr[c].l + tr[c].r) / 2;
    ll lc = 2 * c , rc = 2 * c + 1;
    if(l <= mid) add(lc, l, r, k);
    if(mid+1 <= r) add(rc, l, r, k);
    push_up(c);
}
ll query(ll c,ll l,ll r){
    if(l <= tr[c].l && tr[c].r <= r){
        return tr[c].maxs;
    }
    push_down(c);
    ll mid = (tr[c].l + tr[c].r) / 2 , k = -1e18;
    ll lc = 2 * c , rc = 2 * c + 1;
    if(l <= mid) k = max(k , query(lc, l, r));
    if(mid+1 <= r) k = max(k , query(rc, l, r));
    return k;

}
int main(){
	ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    cin>>n>>q;
    for(int i=1;i<=n;i++) cin>>a[i];
    build(1, 1, n);
    ll opt,l,r,x;
    while(q--){
        cin>>opt>>l>>r;
        if(opt == 1){
            cin>>x;
            update(1, l, r, x);
        }
        else if(opt == 2){
            cin>>x;
            add(1, l, r, x);
        }
        else cout<<query(1, l, r)<<endl;
    }
    return 0;
}

$thx$