#include <bits/stdc++.h>
using namespace std;
const int N = 1e8;
int s[N], ans[1000005];
int main() {
	int c, q;
	cin >> c >> q;
	int sum = 0, len = 1;
	for (int k = 1; k <= q; k++) {
		int a, b, maxn = -1e8, h = 0;;
		cin >> a >> b;
		if(a == 1) {
			for (int i = len; i < len + b; i++)
				s[i] = ++h;
			len += b;
		}
		else if(a == 2) {
			for (int i = 1; i < len - b; i++)
				s[i] = s[i + b];
			len -= b;
		}
		else if(a == 3)
			ans[++sum] =  s[b];
		else if(a == 4) {
			for (int i = 1; i <= len; i++)
				maxn = max(maxn, s[i]);
			ans[++sum] = maxn;
		}
		//for (int i = 1; i < len; i++)
		//	cout << s[i] << " ";
		//cout << endl;
	}
	for (int i = 1; i <= sum; i++)
		cout << ans[i] << endl;
	return 0;
}

大佬求助！