Codeforces 835B

B. The number on the board

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

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

311

output

1

input

399

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.

思路：这题在比赛时一直wa，完全找不出错误，第二天听人一讲题意，原来这题要求的是要变得最少的个数，而不是最小的位数。

代码：

#include <iostream>#include <stdio.h>#include <string.h>#include <cmath>#include <queue>#include <map>#include <algorithm>#include <stdlib.h>using namespace std;#define ma(a) memset(a,0,sizeof(a))#define ll long longint main(){    ll k;    while(cin>>k)    {        char n[111111];        cin>>n;        int len=strlen(n);        sort(n,n+len);        ll sum=0;        int i;        for(i=0;i<len;i++)        {            sum+=n[i]-'0';        }        if(sum>=k)        {            cout<<0<<endl;            continue;        }        ll z=0;        for(i=0;i<len;i++)        {     if(sum<k)z++;            else break;            sum=sum+9-(n[i]-'0');        }        cout<<z<<endl;    }    return 0;}