Give a list of employees (in pairs) that work in the same city. Note: employees SMITH & CLARK work in the same city but ensure we only report this once and not twice (i.e. CLARK & SMITH work in the same city should not be reported!).
Tandaan: empleyado SMITH & CLARK gumana sa parehong lungsod ngunit tiyakin lamang namin ang ulat na ito nang isang beses at hindi dalawang beses (ibig sabihin, CLARK & SMITH gumana sa parehong lungsod ay hindi dapat i-ulat!).