#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

struct dsu {
	vector<int> V;
	dsu(int n) { V.resize(n); rep(i, n) V[i] = i; }
	int root(int a) { if (V[a] == a) return a; return V[a] = root(V[a]); }
	void merge(int r, int s) { V[root(s)] = root(r); }
};

struct RangeProc {
	vector<vector<int>> G;
	vector<int> X;

	void proc() {
		int N = G.size();
		dsu Q(N * 2);
		rep(u, N) for (int v : G[u]) {
			Q.merge(u, v);
		}
		X.resize(N);
		rep(i, N) X[i] = Q.root(i);
	}
};

int main() {
	int N, Q; cin >> N >> Q;
	vector<LL> A(N); rep(i, N) cin >> A[i];
	rep(i, N) if (i % 2 == 1) A[i] = -A[i];
	A.push_back(0);
	for (int i = N - 1; i >= 0; i--) A[i + 1] -= A[i];

	RangeProc G; G.G.resize(N + 1);
	rep(i, Q) {
		int l, r; cin >> l >> r; l--;
		G.G[l].push_back(r);
		G.G[r].push_back(l);
	}
	G.proc();

	vector<LL> S(N + 1);
	rep(i, N + 1) S[G.X[i]] += A[i];
	bool ok = true;
	rep(i, N) if (S[i] != 0) ok = false;
	cout << (ok ? "YES" : "NO") << endl;

	return 0;
}