import sys
from collections import defaultdict

def main():
    N, M = map(int, sys.stdin.readline().split())
    adj = defaultdict(list)
    for _ in range(M):
        u, v = map(int, sys.stdin.readline().split())
        adj[u].append(v)
        adj[v].append(u)
    
    # Collect neighbors of 1
    S = adj[1]
    if len(S) < 2:
        print("NO")
        return
    
    # Precompute for each y, the set of S nodes connected to y
    pre = defaultdict(set)
    for z in S:
        for y in adj[z]:
            pre[y].add(z)
    
    # Iterate through each a in S
    for a in S:
        # Iterate through each neighbor x of a, excluding 1
        for x in adj[a]:
            if x == 1:
                continue
            # Iterate through each neighbor y of x, excluding a
            for y in adj[x]:
                if y == a:
                    continue
                # Check if y has any S nodes connected to it
                if pre[y]:
                    # Check if any of those S nodes is not a
                    has_valid = False
                    for z in pre[y]:
                        if z != a:
                            has_valid = True
                            break
                    if has_valid:
                        print("YES")
                        return
    print("NO")

if __name__ == "__main__":
    main()