//Don't have to see. start------------------------------------------ var read = require('readline').createInterface({ input: process.stdin, output: process.stdout }); var obj; var inLine = []; read.on('line', function(input){inLine.push(input);}); read.on('close', function(){ obj = init(inLine); console.error('\n'); var start = Date.now(); Main(); var end = Date.now() - start; myerr('time : ' + end + 'ms'); myerr('memory : ' + Math.round(process.memoryUsage().heapTotal / 1024) + 'KB'); }); function makeClone(obj){return (obj instanceof Set) ? new Set(Array.from(obj)) : JSON.parse(JSON.stringify(obj));} function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);} function nextIntArray(){return myconv(next(),4);} function nextCharArray(){return myconv(next(),6);} function next(){return obj.next();} function hasNext(){return obj.hasNext();} function init(input){ return { list : input, index : 0, max : input.length, hasNext : function(){return (this.index < this.max);}, next : function(){if(this.hasNext()){return this.list[this.index++];}else{throw 'ArrayIndexOutOfBoundsException ‚There is no more input';}} }; } function myout(s){console.log(s);} function myerr(s){console.error('debug:' + require('util').inspect(s,false,null));} //param "no" is //unknown or outlier : return i. 1: parseInt. //2: split space. 4: split space and parseInt. //6: split 1 character. 7: split 1 character and parseInt. //8: join space. 9: join nextline. 0: join no character. function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(' ');case 4:return i.split(' ').map(Number);case 6:return i.split('');case 7:return i.split('').map(Number);case 8:return i.join(' ');case 9:return i.join('\n');case 0:return i.join('');default:return i;}}catch(e){return i;}} //Don't have to see. end------------------------------------------ function Main(){ var N = nextInt(); for(var i = 0; i < 100; i++){ var tmp = 0; while(N > 0){ tmp += N % 10; N = Math.floor(N / 10); } N = tmp; } myout(N); }