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()){
        // 统计各个字母出现的次数
        let map = {}
        for(let i=0; i< line.length; i++) {
            let cur = line[i]
            if (map[cur]) {
                map[cur] ++
            } else {
                map[cur] = 1
            }
        }
        // 找到字母个数最小的个数
        let min = Math.min(...Object.values(map))
        //删除对应个数的字母
        for (key in map) {
            if (map[key] == min) {
                line = line.replaceAll(key, '')
            }
        }
        console.log(line)
    }
}()