Connect cities

def connect_cities(n, roads):
    from collections import defaultdict

     # Adjacency list
    graph = defaultdict(list)
    for a,b in roads:
        graph[a].append(b)
        graph[b].append(a)

    visited = [False] * (n+1)
    components =[]

    def dfs(node, component):
        visited[node] = True
        component.append(node)
        for neighbour in graph[node]:
            if not visited[neighbour]:
                dfs(neighbour, component)

    for i in range(1, n+1):
        if not visited[i]:
            component = []
            dfs(i, component)
            components.append(component)

    return components

def find_roads_to_add(n, roads):
    components = connect_cities(n, roads)
    
    # If there's only one component, no new roads are needed
    if len(components) == 1:
        print(0)
        return

    # We need to connect each component to the next one
    required_roads = []
    for i in range(len(components) - 1):
        # Connect the first city in component[i] to the first city in component[i+1]
        city1 = components[i][0]
        city2 = components[i+1][0]
        required_roads.append((city1, city2))
    
    # Step 5: Output the number of roads and the roads themselves
    print(len(required_roads))
    for road in required_roads:
        print(road[0], road[1])

n,m = map(int,input().split())

roads = []
for i in range(int(m)):
    a = tuple(map(int,input().split()))
    roads.append(a)

find_roads_to_add(n, roads)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 56, in <module>
    f...

Test 7

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 56, in <module>
    f...

Test 8

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 56, in <module>
    f...

Test 9

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 56, in <module>
    f...

Test 10

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "/box/input/code.py", line 56, in <module>
    f...

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED