#include <bits/stdc++.h> using namespace std; int n,m; vector<int> node[4010],rnode[4010]; int color[4010]; bool visited[4010]; int cnt=0; vector<int> start; bool cross(int a1,int a2,int b1,int b2){ if(a1<=b1&&b1<=a2) return true; if(a1<=b2&&b2<=a2) return true; if(a1<=b1&&b2<=a2) return true; if(b1<=a1&&a2<=b2) return true; return false; } void dfs1(int now){ visited[now]=true; for(int i=0;i<(int)node[now].size();i++){ int next=node[now][i]; if(!visited[next]){ dfs1(next); } } start.push_back(now); } void rdfs(int now,int group){ visited[now]=true; for(int i=0;i<(int)rnode[now].size();i++){ int next=rnode[now][i]; if(!visited[next]) rdfs(next,group); } color[now]=group; } void scc(){ for(int i=0;i<4010;i++) visited[i]=false; start.clear(); for(int i=0;i<2*n;i++){ if(!visited[i]) dfs1(i); } for(int i=0;i<4010;i++) visited[i]=false,color[i]=0; int cnt=1; for(int i=(int)start.size()-1;i>=0;i--){ if(!visited[start[i]]) rdfs(start[i],cnt++); } } int main(){ scanf("%d %d",&n,&m); int l[n],r[n]; for(int i=0;i<n;i++) scanf("%d %d",&l[i],&r[i]); for(int i=0;i<n;i++){ for(int j=i+1;j<n;j++){ if(l[i]<=r[j]&&l[j]<=r[i]){ node[2*i].push_back(2*j+1); rnode[2*j+1].push_back(2*i); node[2*j].push_back(2*i+1); rnode[2*i+1].push_back(2*j); } if(m-r[i]-1<=r[j]&&l[j]<=m-l[i]-1){ node[2*i+1].push_back(2*j+1); rnode[2*j+1].push_back(2*i+1); node[2*j].push_back(2*i); rnode[2*i].push_back(2*j); } if(l[i]<=m-l[j]-1&&m-r[j]-1<=r[i]){ node[2*i].push_back(2*j); rnode[2*j].push_back(2*i); node[2*j+1].push_back(2*i+1); rnode[2*i+1].push_back(2*j+1); } if(-r[i]<=-l[j]&&-r[j]<=-l[i]){ node[2*i+1].push_back(2*j); rnode[2*j].push_back(2*i+1); node[2*j+1].push_back(2*i); rnode[2*i].push_back(2*j+1); } } } scc(); for(int i=0;i<n;i++){ if(color[2*i]==color[2*i+1]){ cout<<"NO"<<endl; return 0; } } cout<<"YES"<<endl; return 0; }