#include <bits/stdc++.h>
#pragma GCC optimize("-O2")
using namespace std;
string doSum(string a, string b) {
  if (a.size() < b.size()) swap(a, b);
  int j = a.size() - 1;
  for (int i = b.size() - 1; i >= 0; i--, j--) a[j] += (b[i] - '0');
  for (int i = a.size() - 1; i > 0; i--) {
    if (a[i] > '9') {
      int d = a[i] - '0';
      a[i - 1] = ((a[i - 1] - '0') + d / 10) + '0';
      a[i] = (d % 10) + '0';
    }
  }
  if (a[0] > '9') {
    string k;
    k += a[0];
    a[0] = ((a[0] - '0') % 10) + '0';
    k[0] = ((k[0] - '0') / 10) + '0';
    a = k + a;
  }
  return a;
}
const int LIM = 1e5 + 5, MOD = 1e9 + 7;
const long double EPS = 1e-9;
string minofstrings(string a, string b) {
  if (a.size() == 0) return b;
  if (b.size() == 0) return a;
  if (a.size() > b.size()) return b;
  if (a.size() < b.size()) return a;
  if (a >= b) return b;
  return a;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long l;
  cin >> l;
  string s;
  cin >> s;
  vector<int> v;
  string ans1, ans2, ans3;
  int n = s.length();
  if (s[n / 2] != '0') {
    ans1 = doSum(s.substr(0, n / 2), s.substr(n / 2, n - n / 2));
  } else {
    int g = n / 2;
    int f = -1;
    for (int i = n / 2; i >= 0; --i) {
      if (s[i] != '0') {
        f = i;
        break;
      }
    }
    if (f != -1) ans1 = doSum(s.substr(0, f), s.substr(f, n - f));
  }
  if (s[(n - 1) / 2] != '0') {
    ans2 =
        doSum(s.substr(0, (n - 1) / 2), s.substr((n - 1) / 2, n - (n - 1) / 2));
  } else {
    int g = (n - 1) / 2;
    int f = -1;
    for (int i = (n - 1) / 2; i < n; ++i) {
      if (s[i] != '0') {
        f = i;
        break;
      }
    }
    if (f != -1) ans2 = doSum(s.substr(0, f), s.substr(f, n - f));
  }
  if (s[(n + 1) / 2] != '0') {
    ans3 =
        doSum(s.substr(0, (n + 1) / 2), s.substr((n + 1) / 2, n - (n + 1) / 2));
  } else {
    int g = (n + 1) / 2;
    int f = -1;
    for (int i = (n + 1) / 2; i < n; ++i) {
      if (s[i] != '0') {
        f = i;
        break;
      }
    }
    if (f != -1) ans3 = doSum(s.substr(0, f), s.substr(f, n - f));
  }
  ans1 = minofstrings(ans1, ans2);
  ans1 = minofstrings(ans1, ans3);
  cout << ans1 << '\n';
  return 0;
}
