#include <cstdio>

#define maxn 13

int n, m;

int s[maxn][3];

int f[1 << maxn][maxn * 3];

inline int min(int a, int b) {return a < b ? a : b;}

int main() {

	scanf("%d", &n);

	for (int i = 0; i < n; i++){

		scanf("%d%d%d", s[i], s[i] + 1, s[i] + 2);

		s[i][0]--, s[i][1]--, s[i][2]--;

	}

	int U = 1 << n;

	__builtin_memset(f, 0x3f, sizeof f);

	f[0][0] = 0;

	for (int i = 0; i < U; i++) {

		for (int j = 0; j < n; j++) if (!(i & 1 << j)){

			for (int k = 0; k <= n * 3; k++) {

				int tmp = k;

				if (i & 1 << s[j][0]) tmp--;

				else tmp++;

				if (i & 1 << s[j][1]) tmp--;

				else tmp++;

				if (i & 1 << s[j][2]) tmp--;

				else tmp++;

				f[i | 1 << j][tmp] = min(f[i | 1 << j][tmp], f[i][k] + tmp);

			}

		}

	}

	printf("%d\n", f[U - 1][0]);

	return 0;

}