"""
Task:- The provided code stub will read in a dictionary containing key/value pairs of name:[marks]
for a list of students.Print the average of the marks array for the student name provided,
showing 2 places after the decimal.
Input Format:- The first line contains the integer n , the number of students' records.
The next n lines contain the names and marks obtained by a student, each value separated by a space.
The final line contains query_name, the name of a student to query.
Output Format:- Print one line: The average of the marks obtained by the particular student correct to 2 decimal places.
"""
"""
    3
    Krishna 67 68 69
    Arjun 70 98 63
    Malika 52 56 60
    Malika
"""

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()
    marks = 0
    for i in student_marks[query_name]:
        marks = marks + i
    avg = marks / 3
    print("%.2f" % avg)


