```go
package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	r := bufio.NewReader(os.Stdin)
	n := readInt(r)
	if n < 4 {
		fmt.Println(0)
		return
	}

	type Point struct {
		x, y int
	}
	points := make([]Point, n)
	cols := make([][]int, 100005)
	rows := make([][]int, 100005)
	pointsMap := make(map[int64]struct{}, n)

	for i := 0; i < n; i++ {
		x := readInt(r)
		y := readInt(r)
		points[i] = Point{x, y}
		cols[x] = append(cols[x], y)
		rows[y] = append(rows[y], x)
		pointsMap[int64(x)<<32|int64(y)] = struct{}{}
	}

	ans := 0
	for _, p := range points {
		x, y := p.x, p.y
		if len(cols[x]) < len(rows[y]) {
			for _, y2 := range cols[x] {
				if y2 > y {
					d := y2 - y
					if _, ok := pointsMap[int64(x+d)<<32|int64(y)]; ok {
						if _, ok := pointsMap[int64(x+d)<<32|int64(y2)]; ok {
							ans++
						}
					}
				}
			}
		} else {
			for _, x2 := range rows[y] {
				if x2 > x {
					d := x2 - x
					if _, ok := pointsMap[int64(x)<<32|int64(y+d)]; ok {
						if _, ok := pointsMap[int64(x2)<<32|int64(y+d)]; ok {
							ans++
						}
					}
				}
			}
		}
	}
	fmt.Println(ans)
}

func readInt(r *bufio.Reader) int {
	var n int
	var c byte
	var err error
	for {
		c, err = r.ReadByte()
		if err != nil {
			return 0
		}
		if c >= '0' && c <= '9' {
			break
		}
	}
	n = int(c - '0')
	for {
		c, err = r.ReadByte()
		if err != nil || c < '0' || c > '9' {
			break
		}
		n = n*10 + int(c-'0')
	}
	return n
}
```