#include <iostream>
using std::max;
const int MAX_NUM = 100002;
int pea[MAX_NUM][11];
void setZero ( int t )
{
for ( int i = 0; i <= t; ++i )
{
for ( int j = 0; j != 11; ++ j )
{
pea[i][j] = 0;
}
}
}
int main ()
{
int N,temp = MAX_NUM;
while ( scanf ("%d",&N), N != 0 )
{
setZero ( temp );
int pos,sec;
int maxSec = 0;
for ( int i = 0; i != N; ++i )
{
scanf ( "%d%d",&pos,&sec ) ;
pea[sec][pos] ++ ;
if ( maxSec < sec )
{
maxSec = sec;
}
}
temp = maxSec;
for ( int i = maxSec; i != 0 ; -- i )
{
for ( int j = 0; j != 11; ++ j )
{
if ( j == 0 )
{
pea[i-1][j] += max ( pea[i][0] , pea[i][1] );
}
else if ( j == 10 )
{
pea[i-1][j] += max ( pea[i][9], pea[i][10] );
}
else
{
pea[i-1][j] += max ( max ( pea[i][j-1], pea[i][j] ), pea[i][j+1] );
}
}
}
printf ( "%d\n",pea[0][5] );
}
return 0;
}
using std::max;
const int MAX_NUM = 100002;
int pea[MAX_NUM][11];
void setZero ( int t )
{
for ( int i = 0; i <= t; ++i )
{
for ( int j = 0; j != 11; ++ j )
{
pea[i][j] = 0;
}
}
}
int main ()
{
int N,temp = MAX_NUM;
while ( scanf ("%d",&N), N != 0 )
{
setZero ( temp );
int pos,sec;
int maxSec = 0;
for ( int i = 0; i != N; ++i )
{
scanf ( "%d%d",&pos,&sec ) ;
pea[sec][pos] ++ ;
if ( maxSec < sec )
{
maxSec = sec;
}
}
temp = maxSec;
for ( int i = maxSec; i != 0 ; -- i )
{
for ( int j = 0; j != 11; ++ j )
{
if ( j == 0 )
{
pea[i-1][j] += max ( pea[i][0] , pea[i][1] );
}
else if ( j == 10 )
{
pea[i-1][j] += max ( pea[i][9], pea[i][10] );
}
else
{
pea[i-1][j] += max ( max ( pea[i][j-1], pea[i][j] ), pea[i][j+1] );
}
}
}
printf ( "%d\n",pea[0][5] );
}
return 0;
}