#include < iostream >
#include < cmath >
using   namespace  std;

int  n;
int  p[ 51 ] = { 0 };
int  ans = 0 ;
void  check( int  x, int  y, int  z){
     for ( int  i = 1 ;i <= n; ++ i){
         if (i != x && abs(i - x) == abs(p[i] - p[x]))  return ;
         if (i != y && abs(i - y) == abs(p[i] - p[y]))  return ;
         if (i != z && abs(i - z) == abs(p[i] - p[z]))  return ;
    }
    ans ++ ;
}
int  main()
{
    cin >> n;
     for ( int  i = 1 ;i <= n; ++ i){
         int  j; cin >> j >> p[j];
    }
    ans = 0 ;
     for ( int  i = 1 ;i <= n - 2 ; ++ i)
         for ( int  j = i + 1 ;j <= n - 1 ; ++ j)
             for ( int  k = j + 1 ;k <= n; ++ k){
                 int  tmp = p[i]; p[i] = p[j]; p[j] = p[k]; p[k] = tmp;
                check(i,j,k);
                tmp = p[i]; p[i] = p[j]; p[j] = p[k]; p[k] = tmp;
                check(i,j,k);
                tmp = p[i]; p[i] = p[j]; p[j] = p[k]; p[k] = tmp;
            }
    cout << ans << endl;
     return   0 ;
}