고수님들 반례나 수정할 부분있으면 알려주세용ㅜㅜ

n = list(input())
error = 'C++'
array = []
for i in range(len(n)):
    if ord(n[i]) <= 90 or (n[i] == '_' and n[i+1] == '_') or (i == len(n)-1 and i == '_') or (i == 0 and i == '_'):
        error = 'java'
        break
    if ord(n[i]) != 95 and (ord(n[i]) > 122 or ord(n[i]) < 97):
        error = 'java'
        break
if error == 'java':
    for i in range(len(n)):
        if n[i] == '_' or (i == 0 and ord(n[i]) <= 90):
            error = "Error!"
            break
        if not ((ord(n[i]) <= 122 and ord(n[i]) >= 97) or (ord(n[i]) <= 90 and ord(n[i]) >= 65)):
            error = "Error!"
            break
if error == "Error!":
    print("Error!")
elif error == 'java':
    for i in range(len(n)):
        if ord(n[i]) <= 90:
            array.append('_')
            array.append(chr(ord(n[i])+32))
        else:
            array.append(n[i])
elif error == 'C++':
    for i in range(len(n)):
        if n[i] == '_':
            array.append(chr(ord(n[i+1])-32))
        elif n[i-1] != '_':
            array.append(n[i])
if error != "Error!":
    for i in range(len(array)):
        print(array[i], end='')