code hơi mệt nha bro, sai thì report giùm ạ.

n=int(input())
k=int(input())
K=[]
dem=0
for i in range(1,n+1):
    if i%2==1:
        K.sort()
        K.append(i)
    if i%2==0:
        K.sort(reverse=True)
        K.append(i)
    if sum(K)>k:
        break
if sum(K)<=k:
    print(0)
else:
    for j in K:
        dem+=1
    print(dem-1)