#!/usr/bin/env python3

(n, m), reduce, comb = map(int, input().split()), __import__("functools").reduce, __import__("math").comb
if not all(c == "0" for c in bin(n)[3:]) or m != (dims := len(bin(n)[3:])) * n // 2: exit(print("no"))
edges, node_number, numbers, seen, level, next_level, count = [[] for _ in range(n + 1)], {1: 1}, {1}, {1}, [1], [], 0
for a, b in (map(int, input().split()) for _ in range(m)): (edges[a].append(b), edges[b].append(a))
# if not all(len(edges[i]) == dims for i in range(1, n + 1)): exit(print("no"))  # This check IS necessary after all
while level:
    for curr in level:
        for neigh in edges[curr]:
            if neigh not in seen:
                seen.add(neigh)
                next_level.append(neigh)
    count, level, next_level = count + 1, next_level, []
    # if len(level) != comb(dims, count): exit(print("no"))  # This check IS actually necessary
    if count == 1:
        for i, node in enumerate(level):
            node_number[node] = 2 << i
            numbers.add(2 << i)
    else:
        for node in level:
            new = reduce(lambda a, b: a | b, (node_number[neigh] for neigh in edges[node] if neigh in node_number), 0)
            if new in numbers: exit(print("no"))
            node_number[node] = new
            numbers.add(new)
print("yes")