contract C {
    function f() public pure {
        address a = address(0);
        a = address(1);
        address b = 0x0123456789012345678901234567890123456789;
        b = 0x9876543210987654321098765432109876543210;
        b = 0x9876_5432_1098_7654_3210_9876_5432_1098_7654_3210;
    }
}