package adv2016;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.HashMap;
import java.util.InputMismatchException;
import java.util.Map;
import java.util.Random;

public class N469 {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		Random gen = new Random();
		long B1 = BigInteger.probablePrime(30, gen).longValue();
		long M1 = BigInteger.probablePrime(31, gen).longValue();
		long B2 = BigInteger.probablePrime(30, gen).longValue();
		long M2 = BigInteger.probablePrime(31, gen).longValue();
		int n = ni(), Q = ni();
		long h1 = 0, h2 = 0;
		long[] p1 = new long[n+2];
		p1[0] = 1;
		for(int i = 1;i <= n+1;i++)p1[i] = p1[i-1] * B1 % M1;
		long[] p2 = new long[n+2];
		p2[0] = 1;
		for(int i = 1;i <= n+1;i++)p2[i] = p2[i-1] * B2 % M2;
		
		Map<Long, Integer> when = new HashMap<>();
		when.put(0L, 0);
		for(int i = 0;i < Q;i++){
			char t = nc();
			if(t == '!'){
				int l = ni(), r = ni(), v = ni();
				h1 += v*(sumGP(B1, r, M1) - sumGP(B1, l, M1));
				h2 += v*(sumGP(B2, r, M2) - sumGP(B2, l, M2));
				h1 %= M1; if(h1 < 0)h1 += M1;
				h2 %= M2; if(h2 < 0)h2 += M2;
				when.putIfAbsent(h1<<32|h2, i+1);
			}else{
				out.println(when.get(h1<<32|h2));
			}
		}
	}
	
	public static long sumGP(long a, long n, long mod)
	{
		long smul = 1; // % mod
		long mul = a % mod;
		long ret = 0;
		for(;n > 0;n >>>= 1){
			if((n&1)==1){
				ret = (ret * mul + smul) % mod;
			}
			smul = smul * (mul + 1) % mod;
			mul = mul * mul % mod;
		}
		return ret;
	}

	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new N469().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}