function Main(input) {
    var alp = /[A-Z]/;
    var result;
    
    function isUpperCase(str){
        return str.match(alp);
    }
    
    if(isUpperCase(input)){
        result = "A";
    }else{
        result = "a";
    }
    
    console.log(result);
}

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