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