Connect cities

from collections import defaultdict


def dfs(node: int, visited: list, adj):
    if visited[node - 1]:
        return
    visited[node - 1] = True
    for neighbor in adj[node]:
        if not visited[neighbor - 1]:
            dfs(neighbor, visited, adj)


n, m = [int(x) for x in input().split()]

adj = defaultdict(list)
result = []

for i in range(m):
    a, b = [int(x) for x in input().split()]
    adj[a].append(b)
    adj[b].append(a)

visited = [False] * n

dfs(1, visited, adj)

for node in range(1, n + 1):
    if visited[i - 1]:
        result.append((1, node))
        dfs(node, visited, adj)

print(len(result))
for road in result:
    print(f"{road[0]} {road[1]}")

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 28, in <module>
    i...

Test 7

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 28, in <module>
    i...

Test 8

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 25, in <module>
    d...

Test 9

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 25, in <module>
    d...

Test 10

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 25, in <module>
    d...

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER