let print = this.print || console.log;
let gets = this.gets || ((arr, index) => () => arr[index++])(input, 0);
let n = gets();
let firstNumber = n.substring(0, 1);
let secondNumber = n.substring(1, 2);
let thirdNumber = n.substring(2, 3);
let fourthNumber = n.substring(3);
let sum = (+firstNumber) + (+secondNumber) + (+thirdNumber) + (+fourthNumber);
print(sum);