def isRXCY(s):
    """
    >>> isRXCY('RRCC233')
    False
    >>> isRXCY('R22C22')
    True
    """
    try:
        idx0 = s.index('R')
        idx1 = s.index('C')
    except:
        return False
    if idx0 != -1 and idx1 != -1:
        return any([str(i) in s[idx0+1:idx1] for i in range(10)])
    return False