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(''))
}
}()

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