const input = require('fs').readFileSync('../input.txt').toString().trim();
const N = Number(input);
let result = 0;
for (let i = 0; i < N; i++) {
let sum = 0;
const str = i.toString();
for (let j = 0; j < str.length; j++) {
sum += Number(str[j]);
}
sum += i;
if (sum == N) {
result = i;
break;
}
}
console.log(result);