import sys
sys.setrecursionlimit(20000)


class UnionFindTree:
    def __init__(self, length: int) -> None:
        self.list = [idx for idx in range(length)]
        self.size = [1 for _ in range(length)]

    def get_root(self, idx: int) -> int:
        if self.list[idx] == idx:
            return idx
        self.list[idx] = self.get_root(self.list[idx])
        return self.list[idx]

    def is_same(self, idx1: int, idx2: int) -> bool:
        return self.get_root(idx1) == self.get_root(idx2)

    def merge(self, idx1: int, idx2: int):
        if self.is_same(idx1, idx2):
            return

        idx1_root = self.get_root(idx1)
        idx2_root = self.get_root(idx2)
        if self.size[idx1_root] > self.size[idx2_root]:
            self.list[idx2_root] = idx1_root
            self.size[idx1_root] += self.size[idx2_root]
        else:
            self.list[idx1_root] = idx2_root
            self.size[idx2_root] += self.size[idx1_root]

    def get_size(self, idx: int) -> int:
        return self.size[self.get_root(idx)]


def main():
    N, M = map(int, input().split())
    uft = UnionFindTree(2*N)
    for _ in range(M):
        A, B = map(lambda n: int(n)-1, input().split())
        uft.merge(A*2, B*2+1)
        uft.merge(B*2, A*2+1)
    if all(uft.is_same(idx*2, idx*2+1) for idx in range(N)):
        print("Yes")
    else:
        print("No")


if __name__ == "__main__":
    main()