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.
//package com.company;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Main {
  public static void main(String args[]) throws IOException {
    InputReader r = new InputReader(System.in);
    int k = r.nextInt();
    String n = r.nextString();
    if (n.length() > k) {
      System.out.print(0);
    } else {
      int sum = 0;
      char[] cs = n.toCharArray();
      List<Integer> digits = new ArrayList<>();
      for (char c: cs) {
        int i = Character.getNumericValue(c);
        sum += i;
        digits.add(i);
      }

      if (sum >= k) {
        System.out.print(0);
      } else {
        Collections.sort(digits);
        int result = 0;
        for (int i: digits) {
          int diff = k - sum;
          if (diff > 9 - i) {
            sum += 9 - i;
            ++result;
          } else {
            ++result;
            break;
          }
        }
        System.out.print(result);
      }
    }

  }

//  static List<Integer> getDigits(BigInteger n) {
//    List<Integer> digits = new ArrayList<>();
//    while (n.compareTo(BigInteger.valueOf(0)) == 1) {
//      digits.add(n.mod(BigInteger.valueOf(10)).intValue());
//      n = n.divide(BigInteger.valueOf(10));
//    }
//    return digits;
//  }

  static class InputReader {

    private int c, bufferSize, bufIndex, numBytesRead;

    private final byte[] buf;
    private final java.io.InputStream stream;

    private static final int DEFAULT_BUFFER_SIZE = 1 << 16;
    private static final java.io.InputStream DEFAULT_STREAM = System.in;

    private static final byte EOF = -1; // End Of File (EOF) character
    private static final byte NL = 10; // '\n' - New Line (NL)
    private static final byte SP = 32; // ' '  - Space character (SP)
    private static final byte DASH = 45; // '-'  - Dash character (DASH)
    private static final byte DOT = 46; // '.'  - Dot character (DOT)

    // The maximum number of accurate decimal digits .nextDoubleFast can read
    private static final int MAX_DECIMAL_PRECISION = 21;

    // A character buffer I reuse when reading string data.
    private static char[] charBuffer = new char[128];

    // Lookup tables used for optimizations
    private static byte[] bytes = new byte[58];
    private static int[] ints = new int[58];
    private static char[] chars = new char[128];

    static {
      char ch = ' ';
      int value = 0;
      byte _byte = 0;
      for (int i = 48; i < 58; i++) bytes[i] = _byte++;
      for (int i = 48; i < 58; i++) ints[i] = value++;
      for (int i = 32; i < 128; i++) chars[i] = ch++;
    }

    // double lookup table, used for optimizations.
    private static final double[][] doubles = {
        {0.0d, 0.00d, 0.000d, 0.0000d, 0.00000d, 0.000000d, 0.0000000d, 0.00000000d, 0.000000000d, 0.0000000000d, 0.00000000000d, 0.000000000000d, 0.0000000000000d, 0.00000000000000d, 0.000000000000000d, 0.0000000000000000d, 0.00000000000000000d, 0.000000000000000000d, 0.0000000000000000000d, 0.00000000000000000000d, 0.000000000000000000000d},
        {0.1d, 0.01d, 0.001d, 0.0001d, 0.00001d, 0.000001d, 0.0000001d, 0.00000001d, 0.000000001d, 0.0000000001d, 0.00000000001d, 0.000000000001d, 0.0000000000001d, 0.00000000000001d, 0.000000000000001d, 0.0000000000000001d, 0.00000000000000001d, 0.000000000000000001d, 0.0000000000000000001d, 0.00000000000000000001d, 0.000000000000000000001d},
        {0.2d, 0.02d, 0.002d, 0.0002d, 0.00002d, 0.000002d, 0.0000002d, 0.00000002d, 0.000000002d, 0.0000000002d, 0.00000000002d, 0.000000000002d, 0.0000000000002d, 0.00000000000002d, 0.000000000000002d, 0.0000000000000002d, 0.00000000000000002d, 0.000000000000000002d, 0.0000000000000000002d, 0.00000000000000000002d, 0.000000000000000000002d},
        {0.3d, 0.03d, 0.003d, 0.0003d, 0.00003d, 0.000003d, 0.0000003d, 0.00000003d, 0.000000003d, 0.0000000003d, 0.00000000003d, 0.000000000003d, 0.0000000000003d, 0.00000000000003d, 0.000000000000003d, 0.0000000000000003d, 0.00000000000000003d, 0.000000000000000003d, 0.0000000000000000003d, 0.00000000000000000003d, 0.000000000000000000003d},
        {0.4d, 0.04d, 0.004d, 0.0004d, 0.00004d, 0.000004d, 0.0000004d, 0.00000004d, 0.000000004d, 0.0000000004d, 0.00000000004d, 0.000000000004d, 0.0000000000004d, 0.00000000000004d, 0.000000000000004d, 0.0000000000000004d, 0.00000000000000004d, 0.000000000000000004d, 0.0000000000000000004d, 0.00000000000000000004d, 0.000000000000000000004d},
        {0.5d, 0.05d, 0.005d, 0.0005d, 0.00005d, 0.000005d, 0.0000005d, 0.00000005d, 0.000000005d, 0.0000000005d, 0.00000000005d, 0.000000000005d, 0.0000000000005d, 0.00000000000005d, 0.000000000000005d, 0.0000000000000005d, 0.00000000000000005d, 0.000000000000000005d, 0.0000000000000000005d, 0.00000000000000000005d, 0.000000000000000000005d},
        {0.6d, 0.06d, 0.006d, 0.0006d, 0.00006d, 0.000006d, 0.0000006d, 0.00000006d, 0.000000006d, 0.0000000006d, 0.00000000006d, 0.000000000006d, 0.0000000000006d, 0.00000000000006d, 0.000000000000006d, 0.0000000000000006d, 0.00000000000000006d, 0.000000000000000006d, 0.0000000000000000006d, 0.00000000000000000006d, 0.000000000000000000006d},
        {0.7d, 0.07d, 0.007d, 0.0007d, 0.00007d, 0.000007d, 0.0000007d, 0.00000007d, 0.000000007d, 0.0000000007d, 0.00000000007d, 0.000000000007d, 0.0000000000007d, 0.00000000000007d, 0.000000000000007d, 0.0000000000000007d, 0.00000000000000007d, 0.000000000000000007d, 0.0000000000000000007d, 0.00000000000000000007d, 0.000000000000000000007d},
        {0.8d, 0.08d, 0.008d, 0.0008d, 0.00008d, 0.000008d, 0.0000008d, 0.00000008d, 0.000000008d, 0.0000000008d, 0.00000000008d, 0.000000000008d, 0.0000000000008d, 0.00000000000008d, 0.000000000000008d, 0.0000000000000008d, 0.00000000000000008d, 0.000000000000000008d, 0.0000000000000000008d, 0.00000000000000000008d, 0.000000000000000000008d},
        {0.9d, 0.09d, 0.009d, 0.0009d, 0.00009d, 0.000009d, 0.0000009d, 0.00000009d, 0.000000009d, 0.0000000009d, 0.00000000009d, 0.000000000009d, 0.0000000000009d, 0.00000000000009d, 0.000000000000009d, 0.0000000000000009d, 0.00000000000000009d, 0.000000000000000009d, 0.0000000000000000009d, 0.00000000000000000009d, 0.000000000000000000009d}
    };

    public InputReader() {
      this(DEFAULT_STREAM, DEFAULT_BUFFER_SIZE);
    }

    public InputReader(int bufferSize) {
      this(DEFAULT_STREAM, bufferSize);
    }

    public InputReader(java.io.InputStream stream) {
      this(stream, DEFAULT_BUFFER_SIZE);
    }

    // Designated constructor
    public InputReader(java.io.InputStream stream, int bufferSize) {
      if (stream == null || bufferSize <= 0)
        throw new IllegalArgumentException();
      buf = new byte[bufferSize];
      this.bufferSize = bufferSize;
      this.stream = stream;
    }

    private byte read() throws java.io.IOException {

      if (numBytesRead == EOF) throw new java.io.IOException();

      if (bufIndex >= numBytesRead) {
        bufIndex = 0;
        numBytesRead = stream.read(buf);
        if (numBytesRead == EOF)
          return EOF;
      }

      return buf[bufIndex++];

    }

    private int readJunk(int token) throws java.io.IOException {

      if (numBytesRead == EOF) return EOF;

      // Seek to the first valid position index
      do {

        while (bufIndex < numBytesRead) {
          if (buf[bufIndex] > token) return 0;
          bufIndex++;
        }

        // reload buffer
        numBytesRead = stream.read(buf);
        if (numBytesRead == EOF) return EOF;
        bufIndex = 0;

      } while (true);

    }

    // Reads a 32bit signed integer from input stream
    public int nextInt() throws java.io.IOException {

      if (readJunk(DASH - 1) == EOF) throw new java.io.IOException();
      int sgn = 1, res = 0;

      c = buf[bufIndex];
      if (c == DASH) {
        sgn = -1;
        bufIndex++;
      }

      do {

        while (bufIndex < numBytesRead) {
          if (buf[bufIndex] > SP) {
            res = (res << 3) + (res << 1);
            res += ints[buf[bufIndex++]];
          } else {
            bufIndex++;
            return res * sgn;
          }
        }

        // Reload buffer
        numBytesRead = stream.read(buf);
        if (numBytesRead == EOF) return res * sgn;
        bufIndex = 0;

      } while (true);

    }

    // Reads a 64bit signed integer from input stream
    public long nextLong() throws java.io.IOException {

      if (readJunk(DASH - 1) == EOF) throw new java.io.IOException();
      int sgn = 1;
      long res = 0L;
      c = buf[bufIndex];
      if (c == DASH) {
        sgn = -1;
        bufIndex++;
      }

      do {

        while (bufIndex < numBytesRead) {
          if (buf[bufIndex] > SP) {
            res = (res << 3) + (res << 1);
            res += ints[buf[bufIndex++]];
          } else {
            bufIndex++;
            return res * sgn;
          }
        }

        // Reload buffer
        numBytesRead = stream.read(buf);
        if (numBytesRead == EOF) return res * sgn;
        bufIndex = 0;

      } while (true);

    }

    private void doubleCharBufferSize() {
      char[] newBuffer = new char[charBuffer.length << 1];
      for (int i = 0; i < charBuffer.length; i++) newBuffer[i] = charBuffer[i];
      charBuffer = newBuffer;
    }

    public String nextLine() throws java.io.IOException {

      try {
        c = read();
      } catch (java.io.IOException e) {
        return null;
      }
      if (c == NL) return ""; // Empty line
      if (c == EOF) return null; // EOF

      int i = 0;
      charBuffer[i++] = (char) c;

      do {

        while (bufIndex < numBytesRead) {
          if (buf[bufIndex] != NL) {
            if (i == charBuffer.length) doubleCharBufferSize();
            charBuffer[i++] = (char) buf[bufIndex++];
          } else {
            bufIndex++;
            return new String(charBuffer, 0, i);
          }
        }

        // Reload buffer
        numBytesRead = stream.read(buf);
        if (numBytesRead == EOF)
          return new String(charBuffer, 0, i);
        bufIndex = 0;

      } while (true);

    }


    public String nextString() throws java.io.IOException {

      if (numBytesRead == EOF) return null;
      if (readJunk(SP) == EOF) return null;
      int i = 0;

      do {

        while (bufIndex < numBytesRead) {
          if (buf[bufIndex] > SP) {
            if (i == charBuffer.length) doubleCharBufferSize();
            charBuffer[i++] = (char) buf[bufIndex++];
          } else {
            bufIndex++;
            return new String(charBuffer, 0, i);
          }
        }

        // Reload buffer
        numBytesRead = stream.read(buf);
        if (numBytesRead == EOF) return new String(charBuffer, 0, i);
        bufIndex = 0;

      } while (true);

    }

    public double nextDouble() throws java.io.IOException {
      String doubleVal = nextString();
      if (doubleVal == null) throw new java.io.IOException();
      return Double.valueOf(doubleVal);
    }

    public double nextDoubleFast() throws java.io.IOException {
      c = read();
      int sgn = 1;
      while (c <= SP) c = read(); // while c is either: ' ', '\n', EOF
      if (c == DASH) {
        sgn = -1;
        c = read();
      }
      double res = 0.0;
      // while c is not: ' ', '\n', '.' or -1
      while (c > DOT) {
        res *= 10.0;
        res += ints[c];
        c = read();
      }
      if (c == DOT) {
        int i = 0;
        c = read();
        // while c is digit and we are less than the maximum decimal precision
        while (c > SP && i < MAX_DECIMAL_PRECISION) {
          res += doubles[ints[c]][i++];
          c = read();
        }
      }
      return res * sgn;
    }

    public int[] nextIntArray(int n) throws java.io.IOException {
      int[] ar = new int[n];
      for (int i = 0; i < n; i++) ar[i] = nextInt();
      return ar;
    }

    public long[] nextLongArray(int n) throws java.io.IOException {
      long[] ar = new long[n];
      for (int i = 0; i < n; i++) ar[i] = nextLong();
      return ar;
    }

    public double[] nextDoubleArray(int n) throws java.io.IOException {
      double[] ar = new double[n];
      for (int i = 0; i < n; i++) ar[i] = nextDouble();
      return ar;
    }

    public double[] nextDoubleArrayFast(int n) throws java.io.IOException {
      double[] ar = new double[n];
      for (int i = 0; i < n; i++) ar[i] = nextDoubleFast();
      return ar;
    }

    public String[] nextStringArray(int n) throws java.io.IOException {
      String[] ar = new String[n];
      for (int i = 0; i < n; i++) {
        String str = nextString();
        if (str == null) throw new java.io.IOException();
        ar[i] = str;
      }
      return ar;
    }

    public int[][] nextIntMatrix(int rows, int cols) throws java.io.IOException {
      int[][] matrix = new int[rows][cols];
      for (int i = 0; i < rows; i++)
        for (int j = 0; j < cols; j++)
          matrix[i][j] = nextInt();
      return matrix;
    }

    public long[][] nextLongMatrix(int rows, int cols) throws java.io.IOException {
      long[][] matrix = new long[rows][cols];
      for (int i = 0; i < rows; i++)
        for (int j = 0; j < cols; j++)
          matrix[i][j] = nextLong();
      return matrix;
    }

    public double[][] nextDoubleMatrixFast(int rows, int cols) throws java.io.IOException {
      double[][] matrix = new double[rows][cols];
      for (int i = 0; i < rows; i++)
        for (int j = 0; j < cols; j++)
          matrix[i][j] = nextDoubleFast();
      return matrix;
    }

    public String[][] nextStringMatrix(int rows, int cols) throws java.io.IOException {
      String[][] matrix = new String[rows][cols];
      for (int i = 0; i < rows; i++)
        for (int j = 0; j < cols; j++)
          matrix[i][j] = nextString();
      return matrix;
    }

    // Closes the input stream
    public void close() throws java.io.IOException {
      stream.close();
    }
  }
}
