func_code_string: #include <bits/stdc++.h>   using namespace std;   long long s(long long x) {     long long sum = 0;     while (x) {       sum += x % 10;       x /= 10;     }     return sum;   }   int32_t main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     long long T;     T = 1;     while (T--) {       long long n, i, x, ans = -1;       cin >> n;       x = sqrt(n);       for (i = 1; i <= 90; i++) {         long long l, r;         l = 1;         r = x;         while (l <= r) {           long long m = l + (r - l) / 2;           long long z = m * m + m * i;           if (z == n && s(m) == i)             ans = m, r = m - 1;           else if (z < n)             l = m + 1;           else             r = m - 1;         }       }       cout << ans <<   n ;     }     return 0;   }   