{643 operatii}

var v:array[0..1000000] of longint;
    n,nr:longint;

procedure rezolvare;
var f,g:text;
    i:longint;
begin

nr:=0;
v[0]:=0;

assign(f,'operatii.in'); reset(f);
assign(g,'operatii.out'); rewrite(g);

readln(f,n);
for i:=1 to n do
    begin
    read(f,v[i]);
    if v[i]>v[i-1] then nr:=nr+v[i]-v[i-1];
    end;
writeln(g,nr);
close(f);
close(g);
end;

begin
rezolvare;
end.