package yukicoder;

import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.HashMap;
import java.util.Random;
import java.util.Scanner;

public class Q469 {
	public static void main(String[] args) {
		PrintWriter pw = new PrintWriter(System.out);
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int q = sc.nextInt();
		Random rand = new Random();
		long p2 = 1_000_000_000 + 7;
		long m2 = 1_000_000_000 + 9;
		long p1 = BigInteger.probablePrime(30, rand).longValue();
		long m1 = BigInteger.probablePrime(30, rand).longValue();
		long[] pow1 = new long[n];
		long[] pow2 = new long[n];
		pow1[0] = 1;
		pow2[0] = 1;
		for (int i = 1; i < n; ++i) {
			pow1[i] = pow1[i - 1] * p1 % m1;
			pow2[i] = pow2[i - 1] * p2 % m2;
		}
		long[] accum1 = new long[n];
		long[] accum2 = new long[n];
		accum1[0] = pow1[0];
		accum2[0] = pow2[0];
		for (int i = 1; i < n; ++i) {
			accum1[i] = (accum1[i - 1] + pow1[i]) % m1;
			accum2[i] = accum2[i - 1] + pow2[i];
		}

		HashMap<Long, Integer> map = new HashMap<>();
		map.put(0L, 0);
		long h1 = 0;
		long h2 = 0;
		for (int query = 0; query < q; ++query) {
			String s = sc.next();
			if (s.equals("!")) {
				int l = sc.nextInt();
				int r = sc.nextInt();
				int k = sc.nextInt();
				h1 += (accum1[r - 1] - (l > 0 ? accum1[l - 1] : 0)) * k % m1;
				h2 += (accum2[r - 1] - (l > 0 ? accum2[l - 1] : 0)) * k % m2;
				while (h1 < 0)
					h1 += m1;
				while (h2 < 0)
					h2 += m2;
				h1 %= m1;
				h2 %= m2;
				if (!map.containsKey(h1 << 31 | h2)) {
					map.put(h1 << 31 | h2, query + 1);
				}
			} else {
				pw.println(map.get(h1 << 31 | h2));
			}
		}
		pw.close();
	}
}