var
  x,y : array [1..100] of real;
  x1,x2,y1,y2,maxy : real;
  i,n,nomy : longint;
begin
  for i:=1 to 2 do
    readln(x[i], y[i]);
  maxy:=y[1];
  for i:=1 to 2 do
    if y[i]>maxy then begin
      maxy:=y[i];
      nomy:=i;
    end;
  writeln(maxy);
end.