left = 1
right = 10**3
while left <= right do
	mid = (left + right) / 2
	puts "? #{mid}"
	STDOUT.flush
	str = gets.chomp
	if str == "safe" then
		left = mid + 1
	else
		if mid == 10**3 then
			left = mid-1
			break
		end
		puts "? #{mid+1}"
		STDOUT.flush
		str = gets.chomp
		if str == "safe" then
			left = mid + 1
		else
			right = mid - 1
		end
	end
end

puts left