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 static java.lang.Math.*;

public class Ques2 {

    static class Scan {

        private final InputStream inputStream;
        private final byte[] buffer = new byte[1024];
        private int currentChar;
        private int numChars;
        private SpaceCharFilter filter;

        public Scan() {
            inputStream = System.in;
        }

        public int read() {
            if (numChars==-1)
                throw new InputMismatchException();

            if (currentChar >= numChars) {
                currentChar = 0;
                try {
                    numChars = inputStream.read(buffer);
                }
                catch (IOException e) {
                    throw new InputMismatchException();
                }

                if(numChars <= 0)
                    return -1;
            }
            return buffer[currentChar++];
        }

        public String nextLine() {
            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
            String str = "";

            try {
                str = br.readLine();
            }
            catch (IOException e) {
            }
            return str;
        }

        public int nextInt() {
            int ch = read();

            while(isSpaceChar(ch))
                ch = read();

            int sgn = 1;

            if (ch == '-') {
                sgn = -1;
                ch = read();
            }

            int res = 0;
            do {
                if(ch < '0' || ch > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += ch - '0';
                ch = read();
            }
            while (!isSpaceChar(ch));

            return res * sgn;
        }

        public long nextLong() {
            int ch = read();

            while (isSpaceChar(ch))
                ch = read();

            int sgn = 1;

            if (ch == '-') {
                sgn = -1;
                ch = read();
            }

            long res = 0;

            do {
                if (ch < '0' || ch > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += ch - '0';
                ch = read();
            }
            while (!isSpaceChar(ch));

            return res * sgn;
        }

        public double nextDouble() {
            int ch = read();

            while (isSpaceChar(ch))
                ch = read();

            int sgn = 1;
            if (ch == '-') {
                sgn = -1;
                ch = read();
            }

            double res = 0;
            while (!isSpaceChar(ch) && ch != '.') {
                if (ch == 'e' || ch == 'E')
                    return res * Math.pow(10, nextInt());
                if (ch < '0' || ch > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += ch - '0';
                ch = read();
            }
            if (ch == '.') {
                ch = read();
                double m = 1;
                while (!isSpaceChar(ch)) {
                    if (ch == 'e' || ch == 'E')
                        return res * Math.pow(10, nextInt());
                    if (ch < '0' || ch > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (ch - '0') * m;
                    ch = read();
                }
            }

            return res * sgn;
        }

        public String readString() {
            int ch = read();
            while (isSpaceChar(ch))
                ch = read();

            StringBuilder res = new StringBuilder();

            do {
                res.appendCodePoint(ch);
                ch = read();
            }
            while (!isSpaceChar(ch));

            return res.toString();
        }

        public boolean isSpaceChar(int ch) {
            if (filter != null)
                return filter.isSpaceChar(ch);
            return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t' || ch == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    static class Print {
        private final BufferedWriter bw;

        public Print() {
            this.bw=new BufferedWriter(new OutputStreamWriter(System.out));
        }

        public void print(Object object)throws IOException {
            bw.append(""+object);
        }

        public void println(Object object)throws IOException {
            print(object);
            bw.append("\n");
        }

        public void close()throws IOException {
            bw.close();
        }
    }

    public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        Print pr = new Print();

        int arr[] = new int[10];
        int k, count=0, i, sum=0;
        String str;
        k=sc.nextInt();
        str=sc.next();

        for(i=0; i<str.length(); i++) {
            arr[(int)(str.charAt(i))-48]++;
            sum+=((int)(str.charAt(i))-48);
            if(sum>k) {
                pr.println("0");
                pr.close();
                return;
            }
        }

        sum=k-sum;
        i=9;
        while(i>0 && sum>0) {
            if(arr[9-i]!=0) {
                k = (int) Math.ceil(sum / (float)i);
                if(k>arr[9-i])
                    k=arr[9-i];
                count += k;
                sum = (sum - k * i);
            }
            i--;
        }
        pr.println(count);
        pr.close();

    }

}
