XOR of all elements from 1 to N
def xor_all_elements ( n ) : NEW_LINE INDENT if n & 3 == 0 : NEW_LINE INDENT return n NEW_LINE DEDENT elif n & 3 == 1 : NEW_LINE INDENT return 1 NEW_LINE DEDENT elif n & 3 == 2 : NEW_LINE INDENT return n + 1 NEW_LINE DEDENT else : NEW_LINE INDENT return 0 NEW_LINE DEDENT DEDENT