/*

     题意：每棵树给出坐标和高度，可以往左右倒，也可以不倒

     问最多能砍到多少棵树

     DP：dp[i][0/1/2] 表示到了第i棵树时，它倒左或右或不动能倒多少棵树

     分情况讨论，若符合就取最大值更新，线性dp，自己做出来了:)

 */

 #include <cstdio>

 #include <algorithm>

 #include <cstring>

 #include <cmath>

 #include <iostream>

 using namespace std;

 typedef long long LL;

 const int MAXN = 1e5 + ;

 const int INF = 0x3f3f3f3f;

 LL x[MAXN], h[MAXN];

 LL dp[MAXN][];        //0-l 1-no 2-r

 int main(void)        //Codeforces Round #303 (Div. 2) C. Woodcutters

 {

     //freopen ("C.in", "r", stdin);

     int n;

     while (scanf ("%d", &n) == )

     {

         for (int i=; i<=n; ++i)

         {

             scanf ("%I64d%I64d", &x[i], &h[i]);

         }

         memset (dp, , sizeof (dp));

         dp[][] = dp[][] = ;

         if (x[] + h[] < x[])    dp[][] = ;

         for (int i=; i<=n; ++i)

         {

             LL tmp;

             tmp = max (dp[i-][], dp[i-][]);

             tmp = max (tmp, dp[i-][]);

             dp[i][] = tmp;

             if (x[i] - h[i] > x[i-])

             {

                 dp[i][] = max (dp[i-][], dp[i-][]) + ;

             }

             if (x[i] - x[i-] > h[i-] + h[i])

             {

                 dp[i][] = max (dp[i][], dp[i-][] + );

             }

             if (i < n && x[i] + h[i] < x[i+])

             {

                 dp[i][] = tmp + ;

             }

             if (i == n)    dp[i][] = tmp + ;

         }

         LL ans;

         ans = max (dp[n][], dp[n][]);

         ans = max (ans, dp[n][]);

         printf ("%I64d\n", ans);

     }

     return ;

 }