program prvi;

uses crt, math;

var
  n, p, i, pt, vr:longint;
  a:array of longint;
  l:boolean;

begin
  clrscr;
  readln(n);
  l:=false;
  for i:=1 to n do
    begin
    if i>1 then
      pt:=p;
    if i=n then
      readln(p)
    else
      read(p);
    if i=1 then
      continue;
    if p>pt then
      begin
      vr:=vr+(p-pt);
      l:=true;
      end
    else if vr=0 then
      continue
    else
      begin
      setlength(a, high(a)+2);
      a[high(a)]:=vr;
      vr:=0;
      end;
    end;
  if vr<>0 then
    begin
    setlength(a, high(a)+2);
    a[high(a)]:=vr;
    end;
  if l=true then
    writeln(maxintvalue(a))
  else
    writeln('0');
  //readln;
end.