grade_book = {"Alice": 85, "Bob": 92, "Charlie": 78, "Arindam": 95, "Asad": 88}

total = 0
for s in grade_book.Values():
    total += s
print(f"Average: {total/len(grade_book):.2f}")
best = max(grade_book,key=grade_book.get)
worst = min(grade_book,key=grade_book.get)
print(f"Highest: {best}({grade_book[best]})")
print(f"lowest: {worst}({grade_book[worst]})")

name = input("search student:")
score = grade_book.get(name)
print(f"{name}'s grade: {score}" if score else f"'{name}'not found")