from decimal import Decimal, ROUND_HALF_UP

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()
    
    x = Decimal(str(sum(student_marks[query_name])/3))
    print(x.quantize(Decimal("0.01"), rounding = ROUND_HALF_UP))

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()
    lis=student_marks[query_name]
    average = sum(lis) / len(lis)
    print("{:.2f}".format(average))

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()
    for k, v in student_marks.items():
        if query_name == k:
            result = sum(v) / len(v)
            print(f"{result:.2f}")

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()
sum = 0
for i in student_marks[query_name]:
    sum = sum + i
avg = sum / 3
formatted = "{:.2f}".format(avg)
print(formatted)