#include <stdio.h>
#define int long long
const int N = 1e6 + 10, INF = 1e18;
int n, m;
struct node { int maxn = -INF, tg, tg1 = -INF; } t[N << 2];
inline int ls(int u) { return u << 1; }
inline int rs(int u) { return u << 1 | 1; }
inline int max(int x, int y) { return x > y ? x : y; }
inline void PushUp(int u) { t[u].maxn = max(t[ls(u)].maxn, t[rs(u)].maxn); }
void PushDown(int u) {
	if (t[u].tg1 == -INF) return;
	t[ls(u)].maxn = t[u].tg1; t[rs(u)].maxn = t[u].tg1;
	t[u].tg1 = -INF;
}
void PushDown1(int u) {
	if (!t[u].tg) return;
	PushDown(u);
	t[ls(u)].tg += t[u].tg; t[rs(u)].tg += t[u].tg;
	t[ls(u)].maxn += t[u].tg; t[rs(u)].maxn += t[u].tg;
	t[u].tg = 0;
}
void Build(int l, int r, int u) {
	if (l == r) { scanf("%lld", &t[u].maxn); return; }
	int m = l + r >> 1;
	Build(l, m, ls(u)); Build(m + 1, r, rs(u));
	PushUp(u);
}
void Update1(int L, int R, int x, int l, int r, int u) {
	if (L <= l && r <= R) { t[u].maxn += x; t[u].tg += x; return; }
	PushDown1(u);
	int m = l + r >> 1;
	if (L <= m) Update1(L, R, x, l, m, ls(u));
	if (m < R) Update1(L, R, x, m + 1, r, rs(u));
	PushUp(u);
}
void Update(int L, int R, int x, int l, int r, int u) {
	if (L <= l && r <= R) { t[u].maxn = x; t[u].tg1 = x; return; }
	PushDown(u);
	int m = l + r >> 1;
	if (L <= m) Update(L, R, x, l, m, ls(u));
	if (m < R) Update(L, R, x, m + 1, r, rs(u));
	PushUp(u);
}
int Query(int L, int R, int l, int r, int u) {
	if (L <= l && r <= R) return t[u].maxn;
	PushDown(u); PushDown1(u);
	int maxn = -INF, m = l + r >> 1;
	if (L <= m) maxn = max(maxn, Query(L, R, l, m, ls(u)));
	if (m < R) maxn = max(maxn, Query(L, R, m + 1, r, rs(u)));
	return maxn;
}
signed main() {
	scanf("%lld%lld", &n, &m);
	Build(1, n, 1);
	while (m--) {
		int op, l, r;
		scanf("%lld%lld%lld", &op, &l, &r);
		if (op == 1) { int x; scanf("%lld", &x); Update(l, r, x, 1, n, 1); }
		else if (op == 2) { int x; scanf("%lld", &x); Update1(l, r, x, 1, n, 1); }
		else printf("%lld\n", Query(l, r, 1, n, 1));
	}
	return 0;
}