#include<bits/stdc++.h>
using namespace std;

int read() {
	char ch=getchar();
	int f=1,x=0;
	while(ch<'0'||ch>'9') {
		if(ch=='-')
			f=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9') {
		x=x*10+ch-'0';
		ch=getchar();
	}
	return f*x;
}
char read_char() {
	char ch=getchar();
	while(!isalpha(ch)) {
		ch=getchar();
	}
	return ch;
}

const int MAXN=1e6+10;

int n,m,len[MAXN],lft[MAXN],rgt[MAXN],blkcnt,vf[MAXN],mx[MAXN],bel[MAXN];
int a[MAXN],father[MAXN];
struct query {
	int op,l,r,x;
}q[MAXN];

int find(int x) {
	if(x!=father[x]) {
		father[x]=find(father[x]);
	}
	return father[x];
}

void get(int l,int r) {
	for(int i=l;i<=r;i++) {
		a[i]=a[find(i)];
	}
	for(int i=l;i<=r;i++) {
		vf[a[i]]=0;
		father[i]=i;
	}
}
void build(int l,int r) {
	for(int i=l;i<=r;i++) {
		if(vf[a[i]]) {
			father[i]=vf[a[i]];
		}
		else {
			vf[a[i]]=i;
			mx[bel[i]]=max(mx[bel[i]],a[i]);
		}
	}
}

int main() {
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	
	cin>>n>>m;
	for(int i=1;i<=n;i++) {
		father[i]=i;
	}
	for(int i=1;i<=m;i++) {
		q[i].op=read();q[i].l=read();q[i].r=read();
		if(q[i].op&1) {
			q[i].x=read();
		}
	}
	
	int blklen=sqrt(n);
	for(int i=1;i<=n;i+=blklen) {
		blkcnt++;
		lft[blkcnt]=i;
		rgt[blkcnt]=min(n,i+blklen-1);
		len[blkcnt]=rgt[blkcnt]-lft[blkcnt]+1;
		for(int j=lft[i];j<=rgt[i];j++) {
			bel[j]=i;
		}
	}
	
	for(int i=1;i<=blkcnt;i++) {
		build(lft[i],rgt[i]);
		for(int j=1;j<=m;j++) {
			if(q[j].op==1) {
				if(q[j].l<=lft[i]&&q[j].r>=rgt[i]) {
					int u=vf[q[j].x];
					int v=vf[q[j].x+1];
					if(u&&!v) {
						vf[q[j].x+1]=u;
						a[u]++;
						vf[q[j].x]=0;
						mx[i]=max(mx[i],v);
					}
					else if(u&&v) {
						father[u]=v;
						vf[q[j].x]=0;
					}
				}
				else if(lft[i]<q[j].l&&q[j].l<=rgt[i]) {
					get(lft[i],rgt[i]);
					for(int k=q[j].l;k<=rgt[i];k++) {
						a[k]+=(a[k]==q[j].x);
					}
					build(lft[i],rgt[i]);
				}
				else if(lft[i]<=q[j].r&&q[j].r<rgt[i]) {
					get(lft[i],rgt[i]);
					for(int k=lft[i];k<=q[j].r;k++) {
						a[k]+=(a[k]==q[j].x);
					}
					build(lft[i],rgt[i]);
				}
			}
			
			else {
				if(q[j].l<=lft[i]&&q[j].r>=rgt[i]) {
					q[j].x=max(q[j].x,mx[i]);
				}
				else if(lft[i]<q[j].l&&q[j].l<=rgt[i]) {
					get(lft[i],rgt[i]);
					for(int k=q[j].l;k<=rgt[i];k++) {
						q[j].x=max(q[j].x,a[k]);
					}
					build(lft[i],rgt[i]);
				}
				else if(lft[i]<=q[j].r&&q[j].r<rgt[i]) {
					get(lft[i],rgt[i]);
					for(int k=lft[i];k<=q[j].r;k++) {
						q[j].x=max(q[j].x,a[k]);
					}
					build(lft[i],rgt[i]);
				}
			}
			
		}
	}
	
	for(int i=1;i<=m;i++) {
		if(q[i].op==2) {
			printf("%d\n",q[i].x);
		}
	}

	//fclose(stdin);
	//fclose(stdout);
	return 0;
}
/*
10 3
1 1 5 0
1 1 3 1
2 3 10
*/