#include <bits/stdc++.h>
using namespace std;
int main() {
  char s[50];
  cin >> s;
  long int cot = -1;
  if (strlen(s) < 3 || strlen(s) > 21) {
    cout << "-1";
    return 0;
  };
  char a[50];
  char b[50];
  char c[50];
  for (int i = 1; i < strlen(s) - 1; i++) {
    for (int j = i + 1; j < strlen(s); j++) {
      for (int t = 0; t < 50; t++) {
        a[t] = 0;
        b[t] = 0;
        c[t] = 0;
      }
      for (int t = 0; t < i; t++) a[t] = s[t];
      for (int t = i; t < j; t++) b[t - i] = s[t];
      for (int t = j; t < strlen(s); t++) c[t - j] = s[t];
      if ((((a[0] != '0') || (strlen(a) == 1)) &&
           ((b[0] != '0') || ((j - i <= 1))) &&
           ((c[0] != '0') || (strlen(c) == 1))) &&
          (j - i <= 7) && (i <= 7) && (strlen(s) - j <= 7)) {
        if ((atol(a) <= 1000000) && (atol(b) <= 1000000) &&
            (atol(c) <= 1000000)) {
          long int x = (atol(a)) + (atol(b)) + (atol(c));
          if (cot < x) {
            cot = x;
          }
        }
      }
    }
  }
  cout << cot;
  cin >> cot;
  return 0;
}
