import sys

input = sys.stdin.readline
sys.setrecursionlimit(10**5+1)

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(v):
    global tmp
    for nv in edge[v]:
        if not used[nv]:
            used[nv] = True
            if nv!=N:
                tmp += B[nv]
            dfs(nv)

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

print("YES")