import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)


class UF_tree:
    def __init__(self, n):
        self.root = [-1] * (n + 1)
        self.rank = [0] * (n + 1)

    def find(self, x):
        if self.root[x] < 0:
            return x
        self.root[x] = self.find(self.root[x])
        return self.root[x]

    def isSame(self, x, y):
        return self.find(x) == self.find(y)

    def unite(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return False
        if self.rank[x] < self.rank[y]:
            self.root[y] += self.root[x]
            self.root[x] = y
        else:
            self.root[x] += self.root[y]
            self.root[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
        return True

    def size(self, x):
        return -self.root[self.find(x)]


N, M = map(int, input().split())
uf = UF_tree(N)
deg = [0] * N
for _ in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    uf.unite(a, b)
    deg[a] += 1
    deg[b] += 1

leader = set()
for i in range(N):
    if uf.size(i) > 1:
        leader.add(uf.find(i))

if len(leader) > 1:
    print("NO")
    exit()

odd = 0
even = 0
for d in deg:
    if not d:
        continue
    if d % 2 == 0:
        even += 1
    else:
        odd += 1

if odd == 0 or odd == 2:
    print("YES")
else:
    print("NO")