"use strict"
let a=require('fs').readFileSync('/dev/stdin', 'utf8')
a = arg.trim().split("\n")
a.shift()
let d = a.map(e => {
var r = e.split(" ").map(Number)
return [r[0]-r[1],r[1]+r[0]]
}).sort((a,b) => {
return a[1]-b[1]
})
let s = 0
let P = Number.MIN_SAFE_INTEGER
for (let i=0; i<d.length; i++) {
if (P <= d[i][0]) {
s++
P = d[i][1]
}
}
console.log(s)