var
   a, b, c, d: Integer;
   function min(a,b:longint):longint;
   begin
      if a>b then
         min:=b
      else
         min:=a;
   end;
   function max(a,b:longint):longint;
   begin
      if a>b then
         max:=a
      else
         max:=b;
   end;
begin
   readln(a, b, c, d);
   writeln(min(max(a,b),max(c,d)));
end.