Some natural number was written on the board. Its sum of digits was not less than k. But you were distracted a bit, and someone changed this number to n, replacing some digits with others. It's known that the length of the number didn't change.

You have to find the minimum number of digits in which these two numbers can differ.

Input

The first line contains integer k (1 ≤ k ≤ 109).

The second line contains integer n (1 ≤ n < 10100000).

There are no leading zeros in n. It's guaranteed that this situation is possible.

Output

Print the minimum number of digits in which the initial number and n can differ.

Examples

Input

3
11


Output

1


Input

3
99


Output

0

Note

In the first example, the initial number could be 12.

In the second example the sum of the digits of n is not less than k. The initial number could be equal to n.
import java.io.*;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class B {

    void solve() {
        int k = in.nextInt();
        String n = in.next();
        int sum = 0;
        int[] count = new int[10];
        for (int i = 0; i < n.length(); i++) {
            int x = Character.getNumericValue(n.charAt(i));
            count[x]++;
            sum += x;
            if (sum >= k) {
                out.println(0);
                return;
            }
        }
        int d = k - sum;
        int ans = 0;
        for (int i = 0; i <= 8; i++) {
            int need = (d + 9 - i - 1)/(9 - i);
            if (need <= count[i]) {
                ans+= need;
                out.println(ans);
                return;
            } else {
                ans += count[i];
                d -= (9 - i) * count[i];
            }
        }
        out.println(ans);
    }

    Scanner in;
    PrintWriter out;

    void run() {
        try {
            in = new Scanner(new File("A.in"));
            out = new PrintWriter(new File("A.out"));

            solve();

            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    void runIO() {

        in = new Scanner(System.in);
        out = new PrintWriter(System.out);

        solve();

        out.close();
    }

    class Scanner {
        BufferedReader br;
        StringTokenizer st;

        public Scanner(File f) {
            try {
                br = new BufferedReader(new FileReader(f));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }

        public Scanner(InputStream f) {
            br = new BufferedReader(new InputStreamReader(f));
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                String s = null;
                try {
                    s = br.readLine();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (s == null)
                    return null;
                st = new StringTokenizer(s);
            }
            return st.nextToken();
        }

        private boolean isSpaceChar(int c) {
            return !(c >= 33 && c <= 126);
        }

        private int skip() {
            int b;
            while ((b = read()) != -1 && isSpaceChar(b)) ;
            return b;
        }

        private int read() {
            int res = -1;
            try {
                res = br.read();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return res;
        }

        char[] nextCharArray(int size) {
            char[] buf = new char[size];
            int b = skip(), p = 0;
            while (p < size && !(isSpaceChar(b))) {
                buf[p++] = (char) b;
                b = read();
            }
            return size == p ? buf : Arrays.copyOf(buf, p);
        }

        char[][] nextCharMap(int n, int m) {
            char[][] map = new char[n][];
            for (int i = 0; i < n; i++) {
                map[i] = nextCharArray(m);
            }
            return map;
        }

        boolean hasMoreTokens() {
            while (st == null || !st.hasMoreTokens()) {
                String s = null;
                try {
                    s = br.readLine();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (s == null)
                    return false;
                st = new StringTokenizer(s);
            }
            return true;
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }
    }

    public static void main(String[] args) {
        new B().runIO();
    }
}