const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    // Write your code here
    while(line = await readline()){
        //获取输入,并将其分别分割
        let tokens = line.split('').reverse();
        let newT = [...new Set(tokens)]
        console.log(newT.join(''))
    }
}()