var
  a,t:array[-200005..200005] of longint;
  f,temp:array[-200005..200005] of int64;
  n:longint;
  ans:int64;
function max(xx,yy:int64):int64;
begin
    if xx<=yy then exit(yy);
	exit(xx);
end;

procedure  init;
var i:longint;
begin
   readln(n);
    for i:=1 to n do
	 readln(a[i],t[i]);
end;

function find(xx:longint):longint;
var i,j:longint;
begin
     for i:=xx+1 to n do
		if a[i]<a[xx] then exit(i);
    exit(0);
end;

 procedure  main;
 var i,j:longint;
 begin
    fillchar(f,sizeof(f),0);
	fillchar(temp,sizeof(temp),0);
        f[n]:=int64(a[n]+t[n]);
	 for i:=n-1 downto 1 do
	   begin
          if a[i]>a[i+1] then
		     f[i]:=f[i+1]+int64(t[i])+int64(a[i]+1-a[i+1])
			 else
			   begin
				   j:=find(i);
				   if j=0 then
				      f[i]:=int64(n-i+a[i])+int64(t[i])
					else
					 f[i]:=f[j]+int64(j-i+a[i]-a[j])+int64(t[i]);
			   end;
	   end;
   ans:=0;
    for i:=1 to n do
	  ans:=max(ans,f[i]);
   writeln(ans);
 end;
begin
    assign(input,'boarding.in');reset(input);
    assign(output,'boarding.out');rewrite(output);
	init;main;
	close(input);close(output);
end.