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())) {
let n = parseInt(line);
let sum = 0;
while (n != 0) {
sum = sum + (n % 10);
n = parseInt(n / 10);
}
console.log(sum);
}
})();