process.stdin.resume();
process.stdin.setEncoding('utf8');
// Your code here!

main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"));
function main(inputs){
    var ans = 0;
    inputs[0].split("").forEach(v=>{
        ans += (v-0);
    });
    console.log(ans);

}