Staples Inc.'s first-quarter net income climbed 30 percent as both its North American and international sales improved.The nation's biggest office supply chain, which sells everything from Post-its and pens to computers and cabinets, also lifted the low end of its full-year profit outlook Thursday. It said its outlook anticipates a "modest" economic recovery for the year.For the three months ended May 1, earnings were $188.8 million, or 26 cents per share.