#include <bits/stdc++.h>
using namespace std;
int main() {
  stringstream ss;
  string x, s1, s2, s3;
  long long int a1 = 0, a2 = 0, a3 = 0, sum = -1, q = 0;
  cin >> x;
  int z = x.size();
  for (int i = 1; i < (z - 1); i++) {
    for (int j = 1; j < (z - i); j++) {
      q = 0;
      stringstream ss1, ss2, ss3;
      s1 = x.substr(0, i);
      s2 = x.substr(i, j);
      s3 = x.substr((i + j), (z - i - j));
      if ((s1[0] == '0' && s1.size() > 1) || (s2[0] == '0' && s2.size() > 1) ||
          (s3[0] == '0' && s3.size() > 1))
        continue;
      {
        ss1 << s1;
        ss1 >> a1;
        ss1.clear();
        ss2 << s2;
        ss2 >> a2;
        ss2.clear();
        ss3 << s3;
        ss3 >> a3;
        ss3.clear();
        if (a1 > 1000000 || a2 > 1000000 || a3 > 1000000) continue;
        q = a1 + a2 + a3;
        if (q > sum) sum = q;
      }
    }
  }
  cout << sum << endl;
}
