const Main = input => {
    input = input.trim();
    const ascii = input.charCodeAt(0);

    if(0x41 <= ascii && ascii <= 0x5A) {
        console.log('A');
    } else if(0x61 <= ascii && ascii <= 0x7A) {
        console.log('a');
    }
}
 
Main(require("fs").readFileSync("/dev/stdin", "utf8"));