use proconio::input;

fn main() {
	input! {
		s: String,
	}

    let ans: String = s.chars()
        .enumerate()
        .map(|(i, c)| {
            let base = (c as u8 - b'A') as i32;
            let shift = (i as i32 + 1) % 26;
            let shifted = (base - shift + 26) % 26;

            (shifted as u8 + b'A') as char
        })
        .collect();

	println!("{ans}");
}