program sortt;
var
 n,x,i,j,ans:longint;
 f:text;
 a:array[1..10000]of longint;
 g:array[1..10000]of boolean;
procedure go;
var k,r:longint;
begin
for k:=1 to a[i]-1 do
  if g[k]  then ans:=ans+1;

end;

Begin
assign(f,'sortt.in');reset(f);
readln(f,n);
for i:=1 to n do g[i]:=true;
read(f,a[1]);g[a[1]]:=false;
ans:=a[1]-1;

for i:=2 to n-1 do
 begin
 read(f,a[i]);g[a[i]]:=false;
 if (a[i]<>1) then go;
 end;

close(f);
assign(f,'sortt.out');rewrite(f);
writeln(f,ans);close(f);

end.