import sys

input = sys.stdin.readline

N,M = map(int,input().split())
B = list(map(int,input().split()))
for i in range(1,N,2):
    B[i] = -B[i]
for i in range(N-1,0,-1):
    B[i] -= B[i-1]

edge = [[] for i in range(N+1)]
for _ in range(M):
    l,r = map(int,input().split())
    edge[r].append(l-1)
    edge[l-1].append(r)

used = [False]*(N+1)
tmp = 0

def dfs(s):
    tmp = 0
    used[s] = True
    tmp += B[s]
    stack = [s]
    while stack:
        v = stack.pop()
        for nv in edge[v]:
            if not used[nv]:
                used[nv] = True
                if nv!=N:
                    tmp += B[nv]
                stack.append(nv)
    return tmp

for i in range(N):
    check = used[-1]
    if not used[i]:
        tmp = dfs(i)
        check2 = used[-1]
        if not check and check2:
            continue
        else:
            if tmp!=0:
                exit(print("NO"))

print("YES")