description: This is the easy version of the problem. The only difference from the hard version is that in this version all coordinates are even.
  
  There are n fence-posts at distinct coordinates on a plane. It is guaranteed that no three fence posts lie on the same line.
  
  There are an infinite number of cows on the plane, one at every point with integer coordinates.
  
  Gregor is a member of the Illuminati, and wants to build a triangular fence, connecting 3 distinct existing fence posts. A cow strictly inside the fence is said to be enclosed. If there are an odd number of enclosed cows and the area of the fence is an integer, the fence is said to be interesting.
  
  Find the number of interesting fences.
  
  Input
  
  The first line contains the integer n (3 ≤ n ≤ 6000), the number of fence posts which Gregor can choose to form the vertices of a fence.
  
  Each of the next n line contains two integers x and y (0 ≤ x,y ≤ 10^7, x and y are even), where (x,y) is the coordinate of a fence post. All fence posts lie at distinct coordinates. No three fence posts are on the same line.
  
  Output
  
  Print a single integer, the number of interesting fences. Two fences are considered different if they are constructed with a different set of three fence posts.
  
  Examples
  
  Input
  
  
  3
  0 0
  2 0
  0 4
  
  
  Output
  
  
  1
  
  
  Input
  
  
  5
  0 0
  2 16
  30 14
  4 6
  2 10
  
  
  Output
  
  
  3
  
  Note
  
  In the first example, there is only 1 fence. That fence is interesting since its area is 4 and there is 1 enclosed cow, marked in red.
  
  <image>
  
  In the second example, there are 3 interesting fences. 
  
    * (0,0) — (30,14) — (2,10) 
    * (2,16) — (30,14) — (2,10) 
    * (30,14) — (4,6) — (2,10) 
solution: import java.util.*;
  import java.io.*;
  
  public class codeforces {
  	public static void main(String[] args) throws Exception {
  
  		
  		long n=sc.nextInt();
  		long a=0;
  		long b=0;
  		long c=0;
  		long d=0;
  		facc(60000);
  		long ans=0;
  		for(int i=0;i<n;i++) {
  			int x=sc.nextInt();
  			int y=sc.nextInt();
  			if(x%4==0&&y%4==0) {
  				a++;
  			}else if(x%4!=0&&y%4==0) {
  				b++;
  			}else if(x%4==0&&y%4!=0) {
  				c++;
  			}else {
  				d++;
  			}
  		}
  		ans+=nc(a, 3)+nc(b, 3)+nc(c, 3)+nc(d, 3);
  		ans+=nc(a, 2)*(b+c+d);
  		ans+=nc(b, 2)*(a+c+d);
  		ans+=nc(c, 2)*(b+a+d);
  		ans+=nc(d, 2)*(b+c+a);
  		pw.println(ans);
  		pw.close();
  	}
  	static long Pow(long a, long e, long mod) // O(log e)
  	{
  		a %= mod;
  		long res = 1l;
  		while (e > 0) {
  			if ((e & 1) == 1)
  				res = (res * a) % mod;
  			a = (a * a) % mod;
  			e >>= 1l;
  		}
  		return res;
  	}
  
  	public static pair extendedEuclid(int a, int b)
  	{
  		if(b == 0) { return new pair(1, 0); }
  		pair z=extendedEuclid(b, a % b);
  		long x1 =  z.y;
  		long y1 = z.x - a / b * z.y;
  		return new pair(x1, y1);
  	}
  	public static long GCD(long a, long b) {
  		if (b == 0)
  			return a;
  		if (a == 0)
  			return b;
  		return (a > b) ? GCD(a % b, b) : GCD(a, b % a);
  	}
  
  	public static long LCM(long a, long b) {
  		return a * b / GCD(a, b);
  	}
  
  	public static long modinverse(long a, long mod) {
  		return Pow(a, mod - 2, mod);
  	}
  
  	static void facc(int n) {
  		fac = new long[n];
  		fac[0] = 1;
  		for (int i = 1; i < n; i++) {
  			fac[i] = (fac[i - 1] * i) % mod;
  		}
  	}
  
  	static long nc(long n, long r) {
  		if (n < r)
  			return 0;
  		long ans=1;
  		for(int i=0;i<r;i++) {
  			ans*=n-i;
  		}
  		for(int i=0;i<r;i++) {
  			ans/=(i+1);
  		}
  		return ans;
  	}
  
  	static long np(int n, int r) {
  		return (nc(n, r) * fac[r]) % mod;
  	}
  
  	static long catlan(int n) {
  		nc(0, 1);
  		return ((fac[2 * n] * modinverse(fac[n],mod)) % mod * modinverse(fac[n + 1],mod)) % mod;
  	}
  
  	static class pair implements Comparable<pair> {
  		long x;
  		long y;
   
  		public pair(long x, long y) {
  			this.x = x;
  			this.y = y;
  		}
   
  		public String toString() {
  			return x + " " + y;
  		}
   
  		public boolean equals(Object o) {
  			if (o instanceof pair) {
  				pair p = (pair) o;
  				return p.x == x && p.y == y;
  			}
  			return false;
  		}
   
  		public int hashCode() {
  			return new Double(x).hashCode() * 31 + new Double(y).hashCode();
  		}
   
  		public int compareTo(pair other) {
  			if (this.x == other.x) {
  				return Long.compare(this.y, other.y);
  			}
  			return Long.compare(this.x, other.x);
  		}
  	}
  	static long fac[];
  	static class Scanner {
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s) {
  			br = new BufferedReader(new InputStreamReader(s));
  		}
  
  		public Scanner(FileReader r) {
  			br = new BufferedReader(r);
  		}
  
  		public String next() throws IOException {
  			while (st == null || !st.hasMoreTokens())
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public int nextInt() throws IOException {
  			return Integer.parseInt(next());
  		}
  
  		public long nextLong() throws IOException {
  			return Long.parseLong(next());
  		}
  
  		public String nextLine() throws IOException {
  			return br.readLine();
  		}
  
  		public double nextDouble() throws IOException {
  			String x = next();
  			StringBuilder sb = new StringBuilder("0");
  			double res = 0, f = 1;
  			boolean dec = false, neg = false;
  			int start = 0;
  			if (x.charAt(0) == '-') {
  				neg = true;
  				start++;
  			}
  			for (int i = start; i < x.length(); i++)
  				if (x.charAt(i) == '.') {
  					res = Long.parseLong(sb.toString());
  					sb = new StringBuilder("0");
  					dec = true;
  				} else {
  					sb.append(x.charAt(i));
  					if (dec)
  						f *= 10;
  				}
  			res += Long.parseLong(sb.toString()) / f;
  			return res * (neg ? -1 : 1);
  		}
  
  		public long[] nextlongArray(int n) throws IOException {
  			long[] a = new long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
  
  		public Long[] nextLongArray(int n) throws IOException {
  			Long[] a = new Long[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextLong();
  			return a;
  		}
  
  		public int[] nextIntArray(int n) throws IOException {
  			int[] a = new int[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
  
  		public Integer[] nextIntegerArray(int n) throws IOException {
  			Integer[] a = new Integer[n];
  			for (int i = 0; i < n; i++)
  				a[i] = nextInt();
  			return a;
  		}
  
  		public boolean ready() throws IOException {
  			return br.ready();
  		}
  
  	}
  
  	
  	static class tuble implements Comparable<tuble> {
  		int x;
  		int y;
  		int z;
  
  		public tuble(int x, int y, int z) {
  			this.x = x;
  			this.y = y;
  			this.z = z;
  		}
  
  		public String toString() {
  			return x + " " + y + " " + z;
  		}
  
  		public int compareTo(tuble other) {
  			if (this.x == other.x) {
  				if (this.y == other.y) {
  					return this.z - other.z;
  				}
  				return this.y - other.y;
  			} else {
  				return this.x - other.x;
  			}
  		}
  	}
  
  	static long mod = 1000000007;
  	static Random rn = new Random();
  	static Scanner sc = new Scanner(System.in);
  	static PrintWriter pw = new PrintWriter(System.out);
  }