S = str(input())
n = len(S) - 1
if n != 0:
    for i in range(0,len(S) - 1):
        if S[i] == S[i].upper():
            S[i] = S[i].lower()
        else:
            S[i] = S[i].upper()
else:
    if S == S.upper():
        S = S.lower()
    else:
        S = S.upper()

print(S)