var v:array[1..32000] of integer;
k,i,j,nr,numar,n:longint;

f,g:text;
ok:boolean;
begin
assign(f,'operatii.in');reset(f);
assign(g,'operatii.out');rewrite(g);
readln(f,n);
for i:=1 to n do read(f,v[i]);
ok:=false;
while ok=false do
begin
nr:=0;
i:=1;
while ok=false do
begin
if v[i]>0 then begin
for j:=i+1 to n do
if v[j]=v[i] then inc(nr)
else break;
for j:=i to i+nr do
dec(v[j]);
inc(numar);
i:=1;
end;
nr:=0;
inc(i);
ok:=true;
for k:=1 to n do
if v[k]<>0 then begin
ok:=false;
break;
end;
end;
end;
write(g,numar);
close(f);
close(g);
end.