Decrypting Commands

str_line = input()

while True:
    line = input()
    if line == "Finish":
        break
    command_args = line.split()
    command = command_args[0]

    if command == "Replace":
        substring = command_args[1]
        new_substring = command_args[2]
        if substring in str_line:
            str_line = str_line.replace(substring, new_substring)
        print(str_line)
    if command == "Cut":
        start_idx = int(command_args[1])
        end_idx = int(command_args[2])
        if 0 <= start_idx < len(str_line) and start_idx < end_idx < len(str_line):
            str_line = str_line[:start_idx] + str_line[end_idx + 1:]
            print(str_line)
        else:
            print("Invalid indices!")
    if command == "Make":
        if command_args[1] == "Upper":
            str_line = str_line.upper()
            print(str_line)
        elif command_args[1] == "Lower":
            str_line = str_line.lower()
            print(str_line)
    if command == "Check":
        line = command_args[1]
        if line in str_line:
            print(f"Message contains {line}")
        else:
            print(f"Message doesn't contain {line}")
    if command == "Sum":
        start_idx = int(command_args[1])
        end_idx = int(command_args[2])
        if 0 < start_idx < len(str_line) and start_idx < end_idx + 1 < len(str_line):
            substring = str_line[start_idx:end_idx + 1]
            final_sum = 0
            for char in substring:
                final_sum += int(ord(char))
            print(final_sum)
        else:
            print("Invalid indices!")