#include <stdio.h>

int main(void)
{
	int n;
	int a[300] = {0};
	int b[11] = {0};
	int p = 0, op = 0;
	int i, j, k;
	int tmp;

	scanf("%d", &n);

	for (i = 0; i < n * 3; i++)
		scanf("%d", &a[i]);

	for ( i = 0; i < n * 3; i++) 
		b[a[i]]++;

	for (i = 1; i <= 10; i++) {
		p += b[i] / 2;
		b[i] %= 2; 
	}
	
	for (i = 1; i <= 10; i++)
		op += b[i];

	p += op / 4;

	printf("%d\n", p);
		
	return 0;
}