import random

population = list(range(1, 1001))  # 1000 customer IDs

random.seed(42)  # reproducible results
sample = random.sample(population, k=20)

print(f"Population size: {len(population)}")
print(f"Sample size: {len(sample)}")
print(f"First 5 IDs sampled: {sorted(sample)[:5]}")