mod = 1000000007
eps = 10**-9


def main():
    import sys
    from collections import deque
    input = sys.stdin.buffer.readline

    N, M = map(int, input().split())
    B = list(map(int, input().split()))
    B = [b * (-1)**i for i, b in enumerate(B)]
    C = [0] * (N+1)
    C[0] = B[0]
    for i in range(1, N):
        C[i] = B[i] - B[i-1]
    C[N] = -B[-1]
    adj = [[] for _ in range(N + 1)]
    for _ in range(M):
        l, r = map(int, input().split())
        l -= 1
        r -= 1
        adj[l].append(r+1)
        adj[r+1].append(l)

    seen = [0] * (N+1)
    par = [-1] * (N+1)
    dp = [0] * (N+1)
    for v0 in range(N+1):
        if seen[v0]:
            continue
        que = deque()
        que.append(v0)
        seen[v0] = 1
        seq = []
        while que:
            v = que.popleft()
            seq.append(v)
            for u in adj[v]:
                if not seen[u]:
                    par[u] = v
                    que.append(u)
        seq.reverse()
        for v in seq:
            if v != v0:
                x = C[v] - dp[v]
                dp[v] += x
                dp[par[v]] -= x
            else:
                if dp[v] != C[v]:
                    print("NO")
                    exit()
    print("YES")
        

if __name__ == '__main__':
    main()