if name == 'main': n = int(input()) student_marks = {} for _ in range(n): name, *line = input().split() scores = list(map(float, line)) student_marks[name] = scores query_name = input()

score = list(student_marks.get(query_name,[]))
avg_score = sum(score)/len(score) if score else 0
print(f'{avg_score:.2f}')