#include <bits/stdc++.h>
using namespace std;
int main(){
  int N, M;
  cin >> N >> M;
  vector<int> B(N);
  for (int i = 0; i < N; i++){
    cin >> B[i];
    if (i % 2 == 0){
      B[i] *= -1;
    }
  }
  vector<int> L(M), R(M);
  for (int i = 0; i < M; i++){
    cin >> L[i] >> R[i];
    L[i]--;
  }
  vector<long long> A(N + 1);
  A[0] = B[0];
  for (int i = 1; i < N; i++){
    A[i] = B[i] - B[i - 1];
  }
  A[N] = -B[N - 1];
  vector<vector<int>> E(N + 1);
  for (int i = 0; i < M; i++){
    E[L[i]].push_back(R[i]);
    E[R[i]].push_back(L[i]);
  }
  vector<bool> used(N + 1, false);
  for (int i = 0; i <= N; i++){
    if (!used[i]){
      used[i] = true;
      long long sum = 0;
      queue<int> Q;
      Q.push(i);
      while (!Q.empty()){
        int v = Q.front();
        Q.pop();
        sum += A[v];
        for (int w : E[v]){
          if (!used[w]){
            used[w] = true;
            Q.push(w);
          }
        }
      }
      if (sum != 0){
        cout << "NO" << endl;
        return 0;
      }
    }
  }
  cout << "YES" << endl;
}