function main(input) {
  const S = input.trim();
  return S.split("").map((c, i) => {
    const code = c.charCodeAt();
    return String.fromCharCode(65 + ((code - 65 - (i + 1)) % 26 + 26) % 26);
  }).reduce((acc, c) => acc + c, "");
}

// Don't edit this line!
console.log(main(require("fs").readFileSync("/dev/stdin", "utf8")));