program EmberAsh;
const
yy:array[1..12]of integer=(31,28,31,30,31,30,31,31,30,31,30,31);
var
month:array[1..12,1..31]of boolean;
year:array[1..365]of boolean;
i,j,k,n,t1,t2,days,max:longint;
ii,jj,kk:real;
fin,fout:text;

BEGIN
assign(fin,'heaven.in');reset(fin);
assign(fout,'heaven.out');rewrite(fout);
readln(fin,n);
for i:=1 to n do
  begin
  readln(fin,t1,t2);
  month[t1,t2]:=true;
  end;
close(fin);
for i:=1 to 31 do
  if month[1,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 29 do
  if month[2,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 31 do
  if month[3,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 30 do
  if month[4,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 31 do
  if month[5,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 30 do
  if month[6,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 31 do
  if month[7,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 31 do
  if month[8,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 30 do
  if month[9,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 31 do
  if month[10,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 30 do
  if month[11,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
for i:=1 to 31 do
  if month[12,i]=false then
    inc(days)
      else
      begin
      if days>max then max:=days;
      days:=0;
      end;
kk:=max/366;
ii:=kk*24*60*60;
writeln(fout,round(ii));
close(fout);
END.