#include<stdio.h>
 
int P[6][4] = {
	{0,1,2,3},
	{0,1,3,2},
	{0,2,1,3},
	{0,2,3,1},
	{0,3,1,2},
	{0,3,2,1}
};
int x[121], y[121];
int main() {
	int n;
	int i, j, k;
	scanf("%d", &n);
	for (i = 0; i < n; i++)scanf("%d%d", &x[i], &y[i]);
	int ans = 0;
	for (i = 0; i < 6; i++) {
		int a = P[i][1], b = P[i][2], c = P[i][3];
		int M[4][4] = { 0, };
		M[a][b] = M[b][c] = M[c][a] = 1;
		int s = 0;
		for (j = 0; j < n; j++)s += M[x[j]][y[j]];
		if (ans < s)
			ans = s;
	}
	printf("%d", ans);
	return 0;
}

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