#include <bits/stdc++.h>
int main() {
  int n1, n2, n3, m, i, j, k, g, t1, t2, t3, sum, len, flag;
  char s[50];
  while (scanf("%s", s) != EOF) {
    len = strlen(s);
    flag = 1;
    if (len == 3 && s[0] == '0' && s[1] == '0' && s[2] == '0')
      sum = 0;
    else if (len > 21 || len < 3)
      flag = 0;
    else {
      sum = 0;
      for (i = 1; i <= 7; i++) {
        if (i > 1 && s[0] == '0') break;
        n1 = 0;
        t1 = 1;
        for (j = i - 1; j >= 0; j--) {
          n1 += (s[j] - '0') * t1;
          t1 *= 10;
        }
        if (n1 <= 1000000) {
          for (j = 1; j <= len - i - 1; j++) {
            if ((j > 1 && s[i] == '0') || (j > 7)) break;
            n2 = 0;
            t2 = 1;
            for (k = i + j - 1; k >= i; k--) {
              n2 += (s[k] - '0') * t2;
              t2 *= 10;
            }
            if (n2 <= 1000000) {
              n3 = 0;
              t3 = 1;
              if ((len - i - j > 1 && s[i + j] == '0') || (len - i - j > 7))
                continue;
              for (k = len - 1; k >= i + j; k--) {
                n3 += (s[k] - '0') * t3;
                t3 *= 10;
              }
              if (n3 <= 1000000 && n2 <= 1000000 && n1 <= 1000000)
                sum = (sum > (n1 + n2 + n3)) ? sum : (n1 + n2 + n3);
            }
          }
        }
      }
      if (sum == 0) flag = 0;
    }
    if (flag == 0) sum = -1;
    printf("%d\n", sum);
  }
  return 0;
}
