#include <stdio.h>
#define SIZE 12
   
int main()
{
    int arr[SIZE] = {4, 1, 2, 8, 9, 5, 1, 7, 8, 8, 6};
	int frequency [10] = {0};
     
    for (int i = 0; i < SIZE; i++) {
        frequency[arr[i]]++;
    }
	
	int count = 0;
	for (int i = 0; i < 10; i++) {
		if (frequency[i] > 1)
			count++;
    }
	printf("%d\n", count);
        
    return 0;
}
   
   
   
/*
run:
   
2
     
*/