Anybody Help Me Please! My program can't pass 6 test Please Write which mistake I have made in my program.

var n,m,b:int64;
begin read(n,m);
      if (m=1)or(n=1) then b:=1
      else if M>=n then b:=n*2-2
      else if n>m then b:=m*2-1;
      writeln(b);
end.

When n=1, answer is 0.