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 static java.lang.Double.parseDouble;
import static java.lang.Long.max;
import static java.lang.Long.min;
import static java.lang.Integer.max;
import static java.lang.Integer.min;
import static java.lang.Integer.parseInt;
import static java.lang.Long.parseLong;
import static java.lang.StrictMath.abs;
import static java.lang.System.err;
import static java.lang.System.exit;
import static java.util.Arrays.sort;

import java.io.*;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.*;


public class A {

    static BufferedReader in;
    static PrintWriter out;
    static StringTokenizer tok;

    static void solve() throws Exception {
        int k = nextInt(), sum = 0, ans = 0;
        char[] s = next().toCharArray();
        Arrays.sort(s);
        for(char c:s) sum += (c - '0');
        int i=0;
        for(char c:s) {
            if(sum>=k) break;
            ans++;
            sum+=('9'-c);
            if(sum>=k) break;
        }
        out.print(ans);
    }

    public static int[] convertIntegers(List<Integer> integers) {
        int[] ret = new int[integers.size()];
        for (int i = 0; i < ret.length; i++) {
            ret[i] = integers.get(i).intValue();
        }
        return ret;
    }

    public static int lower_bound(int[] nums, int target) {
        int low = 0, high = nums.length - 1;
        while (low < high) {
            int mid = low + (high - low) / 2;
            if (nums[mid] < target)
                low = mid + 1;
            else
                high = mid;
        }
        return nums[low] == target ? low : -1;
    }

    public static int upper_bound(int[] nums, int target) {
        int low = 0, high = nums.length - 1;
        while (low < high) {
            int mid = low + (high + 1 - low) / 2;
            if (nums[mid] > target)
                high = mid - 1;
            else
                low = mid;
        }
        return nums[low] == target ? low : -1;
    }

    static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    }

    static char nextChar() throws IOException {
        return next().toCharArray()[0];
    }

    static int nextInt() throws IOException {
        return parseInt(next());
    }

    static long nextLong() throws IOException {
        return parseLong(next());
    }

    static double nextDouble() throws IOException {
        return parseDouble(next());
    }

    static String next() throws IOException {
        while (tok == null || !tok.hasMoreTokens()) {
            tok = new StringTokenizer(in.readLine());
        }
        return tok.nextToken();
    }

    public static void main(String[] args) {
        try {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(new OutputStreamWriter(System.out));
            solve();
            long lEndTime = System.currentTimeMillis();
            //System.out.println("Elapsed time in seconds: " + (double)(lEndTime - lStartTime) / 1000.0);
            in.close();
            out.close();
        } catch (Throwable e) {
            e.printStackTrace();
            exit(1);
        }
    }
}