def calculator(a, b, op):
    if op == '+': return a + b
    if op == '-': return a - b
    if op == '*': return a * b
    if op == '/': return a / b if b else "Error: Division by zero"
    return "Invalid operation"

a, op, b = input("Enter expression (e.g., 5 + 3): ").split()
print("Result:", calculator(float(a), float(b), op))