program MayLava;
const
 month:array[1..12]of integer=(31,29,31,30,31,30,31,31,30,31,30,31);
var
 day:array[0..367]of boolean;
procedure start;
 var
  i,j,n,mm,dd,tt:integer;
  f:text;
 begin
  assign(f,'heaven.in');
  reset(f);
  fillchar(day,sizeof(day),true);
  readln(f,n);
  for i:=1 to n do begin
   readln(f,mm,dd);
   tt:=0;
   for j:=1 to mm-1 do
    tt:=tt+month[j];
   tt:=tt+dd;
   day[tt]:=false;
  end;
  day[367]:=false;
 end;
procedure main;
 var
  i,max,dd:integer;
  f:text;
 begin
  assign(f,'heaven.out');
  rewrite(f);
  max:=0;
  dd:=0;
  for i:=1 to 367 do
   if day[i] then dd:=dd+1
   else begin
    if dd>max then max:=dd;
    dd:=0;
   end;
  writeln(f,round((max/366)*24*60*60));
  close(f);
 end;
BEGIN
 start;
 main;
END.