'use strict'
const main = arg => {
	const input = arg.trim().split("\n");
	let N = Number(input[0])
	let Xs = input.slice(1, input.length).map((x) => {
		return { 
			start : Number(x.split(' ')[0]) - Number(x.split(' ')[1]), 
			end: Number(x.split(' ')[0]) + Number(x.split(' ')[1])
		}
	})
	Xs.sort((a, b) => a.start - b.start)
	let rs = []
	rs.push(Xs[0])
	for(let i = 1 ; i < Xs.length ; i++) {
		// 前のロボットとかぶらない
		if(rs[rs.length - 1].end <= Xs[i].start) {
			rs.push(Xs[i])
		}
	}
	console.log(rs.length)
}   

main(require('fs').readFileSync('/dev/stdin', 'utf8'));