function Main(input) {
  const isUpperCase = c => {
    return /^[A-Z]+$/g.test(c)  
  }
  var tmp = input.trim();
  if (isUpperCase(tmp)){
    console.log('A');}
    else {console.log('a')};
  }

  Main(require("fs").readFileSync("/dev/stdin", "utf8"));