#include<bits/stdc++.h>
using namespace std;
#define int long long
int n, m;
int a[1000100];
struct QvQ {
	int sum, mark , mul;
} tree[4000100];
void build(int l, int r, int id) {
	tree[id].mark=0;
	tree[id].mul=1e18+1;
	if (l == r) {
		tree[id].sum = a[l];
		return;
	}
	int mid = (l + r) / 2;
	build(l, mid, id * 2);
	build(mid + 1, r, id * 2 + 1);
	tree[id].sum = max(tree[id * 2].sum , tree[id * 2 + 1].sum);
	return;
}
void pushdown(int id, int l1, int r1, int l2, int r2) {
	if(tree[id].mul!=1e18+1){
		tree[id * 2].sum = tree[id].mul;
		tree[id * 2 + 1].sum = tree[id].mul;
		tree[id * 2].mark = 0;
		tree[id * 2 + 1].mark = 0;
		tree[id * 2].mul = tree[id].mul;
		tree[id * 2 + 1].mul = tree[id].mul;
		tree[id].mul = 1e18+1;
		//return;
	}
	tree[id * 2].sum +=  tree[id].mark;
	tree[id * 2].mark = tree[id].mark;
	tree[id * 2 + 1].sum += tree[id].mark;
	tree[id * 2 + 1].mark = tree[id].mark;
	tree[id].mark = 0;
	//tree[id].mul = 1e18+1;
}
int query(int L, int R, int l, int r, int id) {
	if (l <= L && R <= r) {
		return tree[id].sum;
	}
	int ans = -1e18;
	int mid = (L + R) / 2;
	pushdown(id, L, mid, mid + 1, R);
	if (l <= mid) {
		ans = max(ans,query(L, mid, l, r, id * 2));
	}
	if (mid + 1 <= r) {
		ans = max(ans,query(mid + 1, R, l, r, id * 2 + 1));
	}
	return ans;
}
void add1(int L, int R, int l, int r, int id, int k) {
	
	if (l <= L && R <= r) {
		tree[id].sum = k;
		tree[id].mul = k ;
		tree[id].mark = 0;
		return;
	}
	int mid = (L + R) >> 1;
	pushdown(id, L, mid, mid + 1, R);
	if (l <= mid) {
		add1(L, mid, l, r, id * 2, k);
	}
	if (r >= mid + 1) {
		add1(mid + 1, R, l, r, id * 2 + 1, k);
	}
	tree[id].sum = max(tree[id * 2].sum , tree[id * 2 + 1].sum );
	return;
}
void add2(int L, int R, int l, int r, int id, int k) {
	if (l <= L && R <= r) {
		tree[id].sum +=  k ;
		tree[id].mark += k;
		return;
	}
	int mid = (L + R) >> 1;
	pushdown(id, L, mid, mid + 1, R);
	if (l <= mid) {
		add2(L, mid, l, r, id * 2, k);
	}
	if (r >= mid + 1) {
		add2(mid + 1, R, l, r, id * 2 + 1, k);
	}
	tree[id].sum = max(tree[id * 2].sum , tree[id * 2 + 1].sum );
	return;
}
signed main() {
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}

	build(1, n, 1);
	int pd, x, y, k;
	while (m--) {
		cin >> pd >> x >> y;
		if (pd == 1) {
			cin >> k;
			add1(1, n, x, y, 1, k);
		} else if (pd == 2) {
			cin >> k;
			add2(1, n, x, y, 1, k);
		} else {
			cout << query(1, n, x, y, 1)<< endl;
		}
	}
	return 0;
}