#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <iomanip>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <cmath>
#include <sstream>
#include <string>
#include <memory.h>

using namespace std;

void prepare()
{
#ifdef _DEBUG
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
#endif
cin.sync_with_stdio(false);
cout.sync_with_stdio(false);
}

const int MAXINT = 200001;
int t[MAXINT + 1], MAX[MAXINT + 1], n;

void rec(int i, int value)
{
    MAX[i] = value;
    if (t[i] > 0 && i + t[i] <= MAXINT && MAX[i + t[i]] <= value)
        rec(i + t[i], value + 1);
}

int main()
{
    prepare();
    cin >> n;

    for (int i = 0; i < n; i++)
    {
        int t1, td;
        cin >> t1 >> td;
        t[t1] = max(td, t[t1]);
    }

    for (int i = 0; i < MAXINT + 1; i++)
    {
        MAX[i] = -1;
    }

    //memset(MAX, 255, MAXINT + 1);
    MAX[0] = 0;

    for (int i = 1; i < MAXINT + 1 ; i++)
    {
        MAX[i] = max(MAX[i], MAX[i - 1]);

        if (t[i] > 0 && i + t[i] <= MAXINT && MAX[i + t[i]] <= MAX[i])
            rec(i + t[i], MAX[i] + 1);
    }

    cout << MAX[MAXINT];

    return 0;

}