#include <iostream>
#include <set>
#include <vector>

using namespace std;

set<vector<int> > QSET;

bool isPeaceful( const vector<int> &Q ) {
	vector<bool> LTRB(2*Q.size(), false);
	vector<bool> RTLB(2*Q.size(), false);

	for ( int i = 0; i < Q.size(); i++ ) {
		const int ltrb = Q.size() - 1 - i + Q[i];
		const int rtlb = Q.size() - 1 - i + (Q.size() - 1 - Q[i]);
		if ( LTRB[ltrb] || RTLB[rtlb] ) return false;
		LTRB[ltrb] = true;
		RTLB[rtlb] = true;
	}

	return true;
}

void compute( vector<int> &Q, const int i, const int j, const int k ) {
	const int ic = Q[i];
	const int jc = Q[j];
	const int kc = Q[k];

	Q[i] = jc, Q[j] = kc, Q[k] = ic;
	if ( isPeaceful(Q) ) QSET.insert(Q);
	Q[i] = kc, Q[j] = ic, Q[k] = jc;
	if ( isPeaceful(Q) ) QSET.insert(Q);

	Q[i] = ic, Q[j] = jc, Q[k] = kc;
}

int main() {
	int N, row, col;
	vector<int> Q;

	cin >> N;
	Q.resize(N);
	for ( int i = 0; i < N; i++ )
		cin >> row >> col, Q[row-1] = col-1;

	QSET.insert(Q);
	for ( int i = 0; i < N; i++ )
		for ( int j = i+1; j < N; j++ )
			for ( int k = j+1; k < N; k++ ) compute(Q, i, j, k);

	cout << QSET.size()-1 << endl;

	return 0;
}