var a:array [0..1000000] of 0..100000;
  i,n:longint; nr:int64;
  f,t:text;

begin
  assign(f,'operatii.in'); assign(g,'operatii.out');
  reset(f); rewrite(g);
  readln(f,n);
  nr:=0;
  for i:=1 to n do
    begin
    read(f,a[i]);
    if a[i]>a[i-1] then nr:=nr+(a[i]-a[i-1]);
    end;
  writeln(t,nr);
  close(f);
  close(g);
end.