#include using namespace std; typedef long long ll; typedef pair< int, int > pii; typedef vector< int > vi; typedef vector< vi > vvi; typedef vector< ll > vl; typedef vector< vl > vvl; typedef vector< pii > vp; typedef vector< vp > vvp; typedef vector< string > vs; typedef vector< double > vd; typedef vector< vd > vvd; template< class T1, class T2 > int upmin( T1 &x, T2 v ){ if( x > v ){ x = v; return 1; } return 0; } template< class T1, class T2 > int upmax( T1 &x, T2 v ){ if( x < v ){ x = v; return 1; } return 0; } const int INF = 0x3f3f3f3f; int N; vi X, Y; void init(){ cin >> N; X = Y = vi( N ); for( int i = 0; i < N; ++i ) cin >> X[ i ] >> Y[ i ]; } int cx[ 2000 + 1 ][ 2000 + 1 ]; int cy[ 2000 + 1 ][ 2000 + 1 ]; int eu_dis2( int x, int y, int a, int b ){ int dtx = x - a; int dty = y - b; return dtx * dtx + dty * dty; } void preprocess(){ memset( cx, -1, sizeof( cx ) ); for( int i = 0; i < N; ++i ){ int x = X[ i ], y = Y[ i ]; static const int dx[] = { 0, 1, 0, -1, 1, 1, -1, -1 }; static const int dy[] = { 1, 0, -1, 0, 1, -1, 1, -1 }; int ng = 0; for( int t = 1; t <= 100; ++t ){ for( int di = 0; di < 8; ++di ){ int nx = x / 10 + t * dx[ di ]; int ny = y / 10 + t * dy[ di ]; if( nx < 0 or nx > 2000 or ny < 0 or ny > 2000 ) continue; if( cx[ nx ][ ny ] == -1 ) continue; if( eu_dis2( x, y, cx[ nx ][ ny ], cy[ nx ][ ny ] ) >= 400 ) continue; ng = 1; } } if( ng ) continue; cx[ x / 10 ][ y / 10 ] = x; cy[ x / 10 ][ y / 10 ] = y; } } void solve(){ int ans = 0; for( int i = 0; i <= 2000; ++i ) for( int j = 0; j <= 2000; ++j ) ans += cx[ i ][ j ] != -1; cout << ans << endl; } signed main(){ ios::sync_with_stdio( 0 ); init(); preprocess(); solve(); return 0; }