#include <iostream>
#include <bitset>
#include <algorithm>
#include <memory.h>
#include <utility>
#include <vector>
#include <deque>

#define ll long long

using namespace std;

const int N = (int)5e5 + 7;

int mod = (int)1e9 + 7;
int p = 997;

int mult(int a, int b) {
    return (a * 1LL * b) % mod;
}

int add(int a, int b) {
    return (a + b) % mod;
}

int h[N];
int pw[N];
int n, k;
string s;

int get(int l, int r) {
    return add(h[r], mod - mult(h[l - 1], pw[r - l + 1]));
}

bool bigger(int i1, int i2) {
    int l = -1;
    int r = n - k + 1;
    while (r - l > 1) {
        int mid = (l + r) >> 1;
        if (get(i1, i1 + mid) == get(i2, i2 + mid)) {
            l = mid;
        } else {
            r = mid;
        }
    }
    if (l == n - k) {
        return 0;
    } else {
        //cout << s[i1 + r] << ' ' << s[i2 + r] << endl;
        return (s[i1 + r] > s[i2 + r]);
    }
}

string addstring(string a, string b) {
    string res;
    if (a.size() > b.size()) {
        swap(a, b);
    }
    reverse(a.begin(), a.end());
    while (a.size() < b.size()) {
        a.push_back('0');
    }
    reverse(a.begin(), a.end());
    int carry = 0;
    for (int i = 0; i < a.size(); i++) {
        res.push_back('0');
    }
    for (int i = a.size() - 1; i >= 0; i--) {
        carry += (a[i] - '0') + (b[i] - '0');
        res[i] = '0' + (carry % 10);
        carry /= 10;
    }
    if (carry) {
        res = char(carry + '0') + res;
    }
    return res;
}

main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    //
    pw[0] = 1;
    for (int i = 1; i < N; i++) {
        pw[i] = mult(pw[i - 1], p);
    }
    cin >> n >> k;
    cin >> s;
    int cur = 0;
    while (s[cur] == '0') {
        cur++;
        k--;
        n--;
    }
    s.erase(0, cur);
    s = " " + s;
    for (int i = 1; i <= n; i++) {
        h[i] = add(mult(h[i - 1], p), s[i]);
    }
    int mx = 1;
    for (int i = 2; i + (n - k) <= n; i++) {
        //cout << i << endl;
        if (bigger(i, mx)) {
            mx = i;
        }
    }
    int sum = 0;
    for (int i = 1; i <= n; i++) {
        if (mx <= i && i <= mx + (n - k)) {
            continue;
        }
        sum += (s[i] - '0');
    }
    string a1, a2;
    for (int i = mx; i <= mx + (n - k); i++) {
        a1.push_back(s[i]);
    }
    while (sum > 0) {
        a2.push_back('0' + sum % 10);
        sum /= 10;
    }
    reverse(a2.begin(), a2.end());
    cout << addstring(a1, a2);
}