知道要加离散化但不太会:(

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 500010;
int n, m;
int tree[MAXN];

int lowbit(int x) {
	return x & -x;
}

void update(int x, int d) {
	while (x <= n) {
		tree[x] += d;
		x += lowbit(x);
	}
}

int sum(int x) {
	int ans = 0;
	while (x > 0) {
		ans += tree[x];
		x -= lowbit(x);
	}
	return ans;
}

int main() {
	
	cin >> n >> m;
	int a;
	for (int i = 1; i <= n; i++) {
		cin >> a;
		update(i, a);
	}
	
	int modle, b, c, k;
	while (m--) {
		
		cin >> modle;
		if (modle == 1) {
			cin >> b >> c >> k;
			for (; b <= c; b++)
				update(b, k);
		} else if (modle == 2) {
			cin >> b;
			cout << sum(b) - sum(b - 1) << endl;
		}
			
	}
		
}