var
  a : array [1..100] of longint;
  n,sum,i,k : longint;
begin
  readln(n);
  readln(k);
  for i:=1 to k do
    readln(a[i]);
  for i:=1 to k do
    if a[i]=n then
      sum:=sum+1;
  then writeln('No')
  else
    writeln(i);
end.