Step 1: Setup and Graph Initialization

First, we need to read the number of users (`U`) and operations (`N`). Then, we'll create our adjacency list.

Guidance for Step 1

  • Adjacency List: For `U` users, we need a list containing `U` empty lists. `adj[i]` will store the friends for user `i`.
  • Main Loop: We'll loop `N` times, reading and processing one command on each iteration.
  • Your Task: Fill in the blank to correctly initialize the `adj` list. What syntax creates a new, empty list? 
# Read U and N
U_str, N_str = input().strip().split()
U, N = int(U_str), int(N_str)

# Adjacency list: a list of U empty lists.
adj = [ _________ for _ in range(U)]

# Process N operations
for _ in range(N):
    # Read the full command line
    parts = input().strip().split()
    
    # Get the operation name (e.g., "add", "degree")
    op = parts[0]
    
    if op == "add":
        pass # To be implemented in Step 2

    elif op == "degree":
        pass # To be implemented in Step 3

    elif op == "isfriend":
        pass # To be implemented in Step 3

    elif op == "count_greater":
        pass # To be implemented in Step 4
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