1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 
 5 using namespace std;
 6 
 7 const int maxn=100005;
 8 
 9 int dp[2*maxn];
10 int v[2*maxn];
11 
12 int main()
13 {
14     int n;
15 
16     while(scanf("%d",&n)!=EOF)
17     {
18         int val,cost;
19 
20         for(int i=1;i<=n;i++)
21         {
22             scanf("%d%d",&val,&cost);
23             v[i]=val-cost;
24         }
25 
26         for(int i=n+1;i<2*n;i++)
27             v[i]=v[i-n];
28 
29         dp[0]=0;
30 
31         int sum=0;
32 
33         for(int i=1;i<2*n;i++)
34         {
35             sum+=v[i];
36             if(sum<0)
37             {
38                 sum=0;
39                 dp[i]=0;
40                 continue;
41             }
42             dp[i]=dp[i-1]+1;
43         }
44 
45         int ans=0;
46 
47         for(int i=1;i<2*n;i++)
48             if(dp[i]>ans)
49                 ans=dp[i];
50 
51         if(ans>n)
52             ans=n;
53 
54         printf("%d\n",ans);
55     }
56 
57     return 0;
58 
59 }