const line = readline() const arr = line.split("") const data = {} arr.forEach( item => { if( data[item] ) { data[item] += 1 }else { data[item] = 1 } }) let min = arr.length Object.keys( data ).forEach( key => { if( data[key] < min ) { min = data[key] } }) const targetArr = [] Object.keys( data ).forEach( key => { if( data[key] === min ) { targetArr.push(key) } }) let str = line targetArr.forEach( key => { let reg = new RegExp(key, 'g'); str = str.replace( reg, "" ) }) console.log( str )