Problem:
Score : 300 points

Problem Statement

You are given a sequence of positive integers of length N, a = (a_1, a_2, ..., a_N).
Your objective is to remove some of the elements in a so that a will be a good sequence.

Here, an sequence b is a good sequence when the following condition holds true:

For each element x in b, the value x occurs exactly x times in b.

For example, (3, 3, 3), (4, 2, 4, 1, 4, 2, 4) and () (an empty sequence) are good sequences, while (3, 3, 3, 3) and (2, 4, 1, 4, 2) are not.

Find the minimum number of elements that needs to be removed so that a will be a good sequence.

Constraints

1 \leq N \leq 10^5

a_i is an integer.

1 \leq a_i \leq 10^9

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the minimum number of elements that needs to be removed so that a will be a good sequence.

Sample Input 1

4
3 3 3 3

Sample Output 1

1

We can, for example, remove one occurrence of 3. Then, (3, 3, 3) is a good sequence.

Sample Input 2

5
2 4 1 4 2

Sample Output 2

2

We can, for example, remove two occurrences of 4. Then, (2, 1, 2) is a good sequence.

Sample Input 3

6
1 2 2 3 3 3

Sample Output 3

0

Sample Input 4

1
1000000000

Sample Output 4

1

Remove one occurrence of 10^9. Then, () is a good sequence.

Sample Input 5

8
2 7 1 8 2 8 1 8

Sample Output 5

5

Solution in C (GCC 5.4.1) (judge verdict: Runtime Error)

    #include <stdio.h>
    #include <stdlib.h>
    #include <ctype.h>
    #define MAX_NUMS 100000
     
    int findNum(unsigned long *x, unsigned long a, int n)
    {
      int i;
      for (i = 0; i < n; i++){
        if (x[i] == a) return i;
      }
      return -1;
    }
     
    void deleteNum(unsigned long *x, int index, int n)	//nは削除前の要素数
    {
      int i;
      for(i = index; i < n-1; i++){
        x[i] = x[i+1];
      }
    }
     
    void addNum(unsigned long *x, unsigned long a, int n)
    {
      x[n] = a;
    }
     
    int main(void)
    {
      unsigned long *a, *num, *nums;
      char *str;
      int n, strlen;
      int i, j, t;
      int numlen = 0;	//数値の数格納
      int count = 0;
     
      //要素数取得
      scanf("%d", &n);
      
      //配列確保
      a = (unsigned long *)malloc(sizeof(unsigned long) * n);
      strlen = (n * 11);
      str = (char *)malloc(sizeof(char) * strlen);
      nums = (int *)malloc(sizeof(int) * n);
      num = (unsigned long *)malloc(sizeof(unsigned long) * n);
      
      //文字取得
      getchar();
      gets(str);
     
      i = 0;
      j = 0;
      while(str[i] != '\0'){
        a[j] = 0;
        while(str[i] == ' ')i++;
        while(isdigit(str[i])){
          a[j] *= 10;
          a[j] += str[i] - '0';
          i++;
        }
        if (str[i] == '\0') break;
        j++;
      }
      
      //それぞれの数値の数を数える
      for (i = 0; i < n; i++){
        if ((t = findNum(num, a[i], numlen)) == -1){
          num[numlen] = a[i];
          nums[numlen] = 1;
          numlen++;
        }else{
          nums[t]++;
          if(nums[t] > num[t]){	//いらないので削除
            deleteNum(a, i, n--);
            count++;
            nums[t]--;
          }
        }
      }
      
      
      #ifdef DEBUG
      for (i = 0; i < numlen; i++){
        printf("\'%d\':%d\n",num[i], nums[i]);
      }
      #endif
      
      //少ないものは削除
      for(i = 0; i < numlen; i++){
        if(nums[i] < num[i]){
          count += nums[i];
          deleteNum(num, i, numlen);
          deleteNum(nums, i, numlen);
          numlen--;i--;
        }
        
      }
      
      printf("%d\n", count);
      
      //開放
      free(a);
      free(str);
      free(nums);
      free(num);
      
      return 0;
    }