import sys
input = sys.stdin.readline

n, m = map(int, input().split())

flag = True
lis = [*range(1, n + 1)][::-1]
ans = 0
for k in lis:
	if(m >= k):
		m -= k
		flag = True
		continue
	if(flag):
		ans += 1
	flag = False
print(ans)