var 
 lengmax,i,j,x1,s,x2,y1,y2,leng,temp:integer; 
 begin 
 assign(input, '27-20b.txt'); 
 Readln(s); 
 Readln(x1,x2); 
 leng:=1; 
 lengmax:= 1; 
 for i:=2 to s do 
     begin 
     Readln(y1, y2); 
     if x2 = y1 then begin 
             leng+=1;   
             end 
     else if x2 = y2 then  
           begin 
           temp:= y1; y1:= y2; y2:=temp; 
           leng+=1; 
             end 
                   
     else if x1 = y1 then 
           begin 
           temp:=x2; x2:=x1; x1:=temp; 
           leng:=2; 
           end 
     else  
           leng:=1; 
     if leng > lengmax then lengmax:=leng;  
     x1:= y1; 
     x2:= y2; 
 end; 
 Writeln(lengmax); 
 end.