#include<bits/stdc++.h>
int N,M,i,j,L,R,r,C[4096];main(){std::cin>>N>>M;for(i=0;i<N;++i){std::cin>>L>>R;for(j=L;j<=R;++j)C[j]+=1;}for(i=0;i<M;++i)if(C[i]+C[M-i-1]>2)r=1;puts(r?"NO":"YES");}