program operatii;
var n,x,y,i,sum:longint;
    f:text;

begin
assign(f,'operatii.in'); reset(f);
readln(f,n);
x:=0; sum:=0;
for i:=1 to n do begin
    read(f,y);
    if x<y then inc(sum,y-x);
    x:=y;
end;
close(f);
assign(f,'operatii.out'); rewrite(f);
writeln(f,sum);
close(f);
end.