def main(n: int, name_and_marks: str, query_name: str) -> float:
    if not isinstance(n, int) or n <= 0:
        raise ValueError("n must be a positive integer")
    if not isinstance(name_and_marks, str):
        raise TypeError("name_and_marks must be in str format")
    if not isinstance(query_name, str):
        raise ValueError("query_name must be a string")

    lines = name_and_marks.strip().splitlines()
    name_and_marks_dict = {}

    for line in lines:
        parts = line.split()
        name = parts[0]
        scores = list(map(float, parts[1:]))
        name_and_marks_dict[name] = scores

    if query_name in name_and_marks_dict:
        scores = name_and_marks_dict[query_name]
        return round(sum(scores) / len(scores), 2)
    else:
        raise ValueError(f"{query_name} not found in the records.")

    
if __name__ == '__main__':
    n = int(input())
    name_and_marks = "\n".join(input() for _ in range(n))
    query = input()
    result = main(n, name_and_marks, query)
    print(f"{result:.2f}")