program gaidziai;
var	pomidorai: array [1..70] of integer;
	i, j, n, p, d: integer;
begin
	writeln('ivesk pomidoru skaiciu, prinokusio pomidoro numeri ir dienu skaiciu');
	readln(n, p, d);
	for i := 1 to n do
		if i = p then pomidorai[i] := 1
		else pomidorai[i] := 0;
	for i := d downto 1 do
		begin
			j := j + 1;
			pomidorai[p+j] := 1;
			pomidorai[p-1] := 1;
		end;
	j := 0;
	for i := 1 to n do
		if pomidorai[i] := 0 then j := j + 1;
	writeln(j);
	readln;
end.