package main

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

func main() {
	in := bufio.NewReader(os.Stdin)
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	var n int
	if _, err := fmt.Fscan(in, &n); err != nil {
		return
	}

	diff := make([]int64, 3005)
	sum := make([]int64, 3005)

	for i := 0; i < n; i++ {
		var x, y int
		fmt.Fscan(in, &x, &y)
		d := x - y + 1000
		s := x + y
		diff[d]++
		sum[s]++
	}

	var ans int64
	for _, c := range diff {
		if c > 1 {
			ans += c * (c - 1) / 2
		}
	}
	for _, c := range sum {
		if c > 1 {
			ans += c * (c - 1) / 2
		}
	}

	fmt.Fprintln(out, ans)
}