1 #include <iostream>
 2 #include <algorithm>
 3 #include <cstring>
 4 #include <cstdio>
 5 #include <cmath>
 6 
 7 using namespace std;
 8 
 9 int n,t,x,maxtime;
10 long long ans;
11 const int N=1E5+7;
12 int a[N][15],dp[N][15];
13 
14 int MAX(int a,int b,int c)
15 {
16     int res = -1;
17     if ( a>res )
18         res = a;
19     if ( b>res )
20         res = b;
21     if ( c>res )
22         res = c;
23     return res;
24 }
25 
26 int main()
27 {
28     while ( scanf("%d",&n)!=EOF&&n )
29     {
30         ans = -1 ;
31         maxtime = -1;
32         memset(a,0,sizeof(a));
33         memset(dp,0,sizeof(dp));
34         for ( int i = 1 ; i <= n ; i++ )
35         {
36             scanf("%d %d",&x,&t);
37             a[t][x]++;
38             if ( t>maxtime )
39                 maxtime = t;
40         }
41         dp[1][4] = a[1][4];
42         dp[1][5] = a[1][5];
43         dp[1][6] = a[1][6];
44         for ( int i = 2 ; i <= maxtime ; i++ )
45             for ( int j = 0 ; j <= 10 ; j++ )
46             {
47                 if ( j==0 )
48                     dp[i][j] = max(dp[i-1][j],dp[i-1][j+1]) + a[i][j];
49                     else if ( j==10 )
50                             dp[i][j] = max(dp[i-1][j],dp[i-1][j-1]) + a[i][j];
51                             else  dp[i][j] = MAX(dp[i-1][j-1],dp[i-1][j],dp[i-1][j+1])+a[i][j];
52                // if ( dp[i][j]>ans )
53               //      ans = dp[i][j];
54              
55             }
56             for ( int i = 0 ; i <= 10 ; i++)
57                 if ( dp[maxtime][i]>ans )
58                    ans = dp[maxtime][i];
59         printf("%I64d\n",ans);
60 
61     }
62     return 0;
63 }

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cmath>

using namespace std;

int n,t,x,maxtime;
long long ans;
const int N=1E5+7;
int a[N][15],dp[N][15];

int MAX(int a,int b,int c)
{
    int res = -1;
    if ( a>res )
        res = a;
    if ( b>res )
        res = b;
    if ( c>res )
        res = c;
    return res;
}

int main()
{
    while ( scanf("%d",&n)!=EOF&&n )
    {
        ans = -1 ;
        maxtime = -1;
        memset(a,0,sizeof(a));
        memset(dp,0,sizeof(dp));
        for ( int i = 1 ; i <= n ; i++ )
        {
            scanf("%d %d",&x,&t);
            a[t][x]++;
            if ( t>maxtime )
                maxtime = t;
        }
        dp[1][4] = a[1][4];
        dp[1][5] = a[1][5];
        dp[1][6] = a[1][6];
        for ( int i = 2 ; i <= maxtime ; i++ )
            for ( int j = 0 ; j <= 10 ; j++ )
            {
                if ( j==0 )
                    dp[i][j] = max(dp[i-1][j],dp[i-1][j+1]) + a[i][j];
                    else if ( j==10 )
                            dp[i][j] = max(dp[i-1][j],dp[i-1][j-1]) + a[i][j];
                            else  dp[i][j] = MAX(dp[i-1][j-1],dp[i-1][j],dp[i-1][j+1])+a[i][j];
                if ( dp[i][j]>ans )
                    ans = dp[i][j];
             
            }
          //  for ( int i = 0 ; i <= 10 ; i++)
          //      if ( dp[maxtime][i]>ans )
          //         ans = dp[maxtime][i];
        printf("%I64d\n",ans);

    }
    return 0;
}