let input = ['7842'];


let print = this.print || console.log;
let gets = this.gets || ((arr, index) => () => arr[index++])(input, 0);



let inputOne = gets().split('');

if (inputOne[0] === '-') {

  inputOne.shift();

}






inputOne = inputOne.map(Number);

  console.log(inputOne);

  let sum = 0;

  let sum2 = 0;

  let str = [];






  for (let i = 0; i < inputOne.length; i++) {

      sum = sum + inputOne[i];


  }





  while (sum > 9) {

     str = sum.toString();

    str = str.split('').map(Number);
     console.log(str);

      sum = 0;

    for (let j = 0; j < str.length; j++) {


      sum = sum + str[j];

    }

  }

  console.log(sum);