function Main(input) {
  input.trim();
  input = input.split("\n");
  var N = input[0];
  input.shift();
  var arr = arr1dto2d(input);
  var sum = 0;
  for(var p=0;p<N;p++){
    var mem = arr[p];
    var ato = mem[0];
    arr[p][0] -= mem[1];
    arr[p][1] += ato;
  }
  arr.sort(function(a,b){return(a[1] - b[1]);});
  var P = -900000000000;
  for(var i=0;i<N;i++){
    if(P<=arr[i][0]){
      sum++;
      P = arr[i][1];
    }
  }
  console.log(sum);
}Main(require("fs").readFileSync("/dev/stdin", "utf8").trim());
function arr1dto2d (arr){
	for(var i=0;i<arr.length;i++){
    arr[i]=arr[i].split(" ").map(Number);
    }
  return arr;
}