Program operatii;
 var prec,now,i,n:longint;
     rez:int64;
     b1:array [1..1 shl 15] of char;
     fi,fo:text;
begin
 assign(fi,'operatii.in');
  assign(fo,'operatii.out');
 settextbuf(fi,b1);
 reset(fi); rewrite(fo);
 readln(fi,n);
 for i:=1 to n do begin
                    read(fi,now);
                     if now>prec then rez:=rez+now-prec;
                    prec:=now;
                  end;
  write(fo,rez);
 close(fo);
end.