Building Teams

line = input()

parts = line.split(" ")
pupils, friendships = int(parts[0]), int(parts[1])

adj: dict[int, list[int]] = {}
for i in range(1, pupils + 1):
    adj[i] = []

for _ in range(friendships):
    parts = input().split(" ")
    a, b = int(parts[0]), int(parts[1])

    adj[a].append(b)
    adj[b].append(a)


res: list[str] = []
for i in range(pupils+1):
    res.append("0")

def rec(p: int):
    if res[p] == "1":
        return
    if res[p] == "2":
        print("IMPOSSIBLE")
        exit(0)
    res[p] = "1"
    
    for friend in adj[p]:
        res[friend] = "2"

for p in range(1, pupils + 1):
    if res[p] == "0":
        rec(p)

if friendships == 0:
    print("IMPOSSIBLE")
    exit(0)

print(" ".join(res[1:]))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER