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.Arrays;

public class Main {

    private static final int MOD = 1000000007;
    private static final int intINF = Integer.MAX_VALUE;
    private static final long longINF = Long.MAX_VALUE;

    private static void solve() {
        long k=sc.nextInt();sc.nextLine();
        String s=sc.nextLine();
        int[] d = new int[10];
        for (int i=0;i<s.length();i++)d[s.charAt(i)-'0']++;
        long sum = 0;
        for (int i=0;i<10;i++)sum+=d[i]*i;
        int u = 0;
        int ans = 0;
        while(sum<k){
            while (d[u]==0)u++;
            while (d[u]>0 && sum<k){
                d[u]--;
                sum-=u;
                sum+=9;
                ans++;
            }
        }
        pw.print(ans);
    }

    //TEMPLATE

    private static myScanner sc;
    private static PrintWriter pw;

    private static final int numberOfTests = 1;

    private static final String nameOfInAndOutFile = "";
    private static final String fullNameInputFile = nameOfInAndOutFile + ".in";
    private static final String fullNameOutputFile = nameOfInAndOutFile + ".out";

    public static void main(String[] args) throws IOException {
        if (nameOfInAndOutFile.length() == 0) {
            setDefaultInAndOutPut();
        } else {
            setInAndOutPutFromFile();
        }
        for (int test = 1; test <= numberOfTests; test++) {
            solve();
            pw.flush();
        }

        pw.close();
    }

    private static void setDefaultInAndOutPut() {
        sc = new myScanner(new BufferedReader(new InputStreamReader(System.in)));
        pw = new PrintWriter(System.out);
    }

    private static void setInAndOutPutFromFile() throws IOException {
        sc = new myScanner(new BufferedReader(new FileReader(new File(fullNameInputFile))));
        pw = new PrintWriter(new File(fullNameOutputFile));
    }
}

class myScanner {
    private char[] buffer = new char[1 << 8];
    private int pos = 1;

    private BufferedReader reader;

    public myScanner(BufferedReader reader) {
        this.reader = reader;
    }

    public boolean hasNext() {
        return pos > 0;
    }

    private void loadBuffer() {
        pos = 0;
        try {
            for (int i; (i = reader.read()) != -1; ) {
                char c = (char) i;
                if (c != ' ' && c != '\n' && c != '\t' && c != '\r' && c != '\f') {
                    if (pos == buffer.length) buffer = Arrays.copyOf(buffer, 2 * pos);
                    buffer[pos++] = c;
                } else if (pos != 0) break;
            }
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }

    public String current() {
        return String.copyValueOf(buffer, 0, pos);
    }


    public String next() {
        loadBuffer();
        return current();
    }


    public String nextLine() {
        try {
            return reader.readLine();
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }


    public int nextInt() {
        return nextInt(10);
    }

    public long nextLong() {
        return nextLong(10);
    }

    public int nextInt(int radix) {
        loadBuffer();
        int result = 0;
        int i = buffer[0] == '-' || buffer[0] == '+' ? 1 : 0;
        for (checkValidNumber(pos > i); i < pos; i++) {
            int digit = buffer[i] - '0';
            checkValidNumber(0 <= digit && digit <= radix - 1);
            result = result * radix + digit;
        }
        return buffer[0] == '-' ? -result : result;
    }

    public long nextLong(int radix) {
        loadBuffer();
        long result = 0;
        int i = buffer[0] == '-' || buffer[0] == '+' ? 1 : 0;
        for (checkValidNumber(pos > i); i < pos; i++) {
            int digit = buffer[i] - '0';
            checkValidNumber(0 <= digit && digit <= radix - 1);
            result = result * radix + digit;
        }
        return buffer[0] == '-' ? -result : result;
    }

    public int[] nextArrayInts(int size) {
        int[] input = new int[size];
        for (int i = 0; i < size; i++) input[i] = nextInt();
        return input;
    }

    public long[] nextArrayLongs(int size) {
        long[] input = new long[size];
        for (int i = 0; i < size; i++) input[i] = nextLong();
        return input;
    }

    public double nextDouble() {
        loadBuffer();
        long result = 0;
        int i = buffer[0] == '-' || buffer[0] == '+' ? 1 : 0;
        long round = 1;
        final int radix = 10;
        boolean hasPoint = false;
        for (checkValidNumber(pos > i); i < pos; i++) {
            int digit = buffer[i] - '0';
            checkValidNumber((0 <= digit && digit <= radix - 1) || (!hasPoint && digit == -2));
            if (digit == -2) hasPoint = true;
            else {
                if (hasPoint) round *= radix;
                result = result * radix + digit;
            }

        }
        return buffer[0] == '-' ? -result / (1.0 * round) : result / (1.0 * round);
    }

    private void checkValidNumber(boolean condition) {
        if (!condition) throw new NumberFormatException(current());
    }
}