for t in range(int(input())):
	n = int(input())
	s = input()
	ans = 0
	if s[0] == '1':
		ans = 1
	for i in range(n - 1):
		if s[i+1] == '1':
			ans = 1
		if s[i] == '1' and s[i+1] == '1':
			ans = 2
			break
	print(ans)