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anton_and_currency_you_all_know.rs
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anton_and_currency_you_all_know.rs
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use std::collections::VecDeque;
use std::io;
fn main() -> io::Result<()> {
let mut scan = Scan::new();
let mut arr: Vec<u8> = scan
.next::<String>()
.chars()
.map(|c| c.to_digit(10).unwrap() as u8)
.collect();
let n = arr.len();
let mut candidates: Vec<usize> = vec![];
for i in 0..(n - 1) {
if arr[i] % 2 == 0 {
candidates.push(i);
if arr[i] < arr[n - 1] {
break;
}
}
}
if candidates.len() == 0 {
println!("-1");
} else {
let &last_i = candidates.last().unwrap();
(arr[n - 1], arr[last_i]) = (arr[last_i], arr[n - 1]);
for x in arr {
print!("{}", x);
}
println!();
}
Ok(())
}
struct Scan {
buffer: VecDeque<String>,
}
impl Scan {
fn new() -> Scan {
Scan {
buffer: VecDeque::new(),
}
}
fn next_line(&self) -> io::Result<String> {
let mut line = String::new();
match io::stdin().read_line(&mut line)? {
0 => Err(io::Error::new(io::ErrorKind::Other, "EOF")),
_ => Ok(line),
}
}
fn next<T: std::str::FromStr>(&mut self) -> T {
loop {
if let Some(token) = self.buffer.pop_front() {
match token.parse() {
Ok(x) => {
return x;
}
_ => {
panic!("parse");
}
}
}
let line = self.next_line().unwrap();
self.buffer = line.split_whitespace().map(String::from).collect();
}
}
}