#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

template<class S, class T>
void psort(vector<S> &u, vector<T> &v, bool isGreater=false){
    int n = (int)u.size();
    vector<pair<S, T>> vecP(n);
    for(int i = 0; i < n; ++i){
        vecP[i].first = u[i];
        vecP[i].second = v[i];
    }
    if(isGreater){
        sort(vecP.rbegin(), vecP.rend());
    } else{
        sort(vecP.begin(), vecP.end());
    }
    for(int i = 0; i < n; ++i){
        u[i] = vecP[i].first;
        v[i] = vecP[i].second;
    }
}

int main(){
    int N, M;
    while(cin >> N >> M){
        vi L(N), R(N);
        rep(i, N){
            scanf("%d%d", &L[i], &R[i]);
            R[i]++;
            int l = M - R[i], r = M - L[i];
            if(l < L[i]){
                L[i] = l;
                R[i] = r;
            }
        }
        psort(L, R);
        vector<vi> dp(N + 1, vi(M, -1));
        dp[0][0] = M;
        rep(i, N){
            rep(l, M)if(dp[i][l] >= l){
                int r = dp[i][l];
                if(l <= L[i] && R[i] <= r)smax(dp[i + 1][R[i]], r);
                int nl = M - R[i], nr = M - L[i];
                if(l <= nl && nr <= r)smax(dp[i + 1][l], nl);
            }
        }
        int ok = 0;
        rep(l, M)ok |= l<=dp[N][l];
        puts(ok ? "YES" : "NO");
    }
}