var v:array[1..100] of integer;
    i,j,n,k:integer;
    f,g:text;
begin
assign(f,'operatii.in');
assign(g,'operatii.out');
reset(f);
rewrite(g);
readln(f,n);
for i:=1 to n do begin
                 read(f,v[i]);
                 if v[i]>v[i-1] then k:=k+v[i]-v[i-1];
                 end;
writeln(g,k);
close(f);
close(g);
end.