n,t=map(int,input().split())
a=[]
for i in range(n):
a.append(str(i))

b=[]
i=0
j=i+1
while i<len(a):
temp=a[i]+' '
for x in range(j,len(a)):
temp+=a[x]+' '
b.append(temp.split())
if j<len(a):
j+=1
else:
i+=1
j=i+1

def xuli(a):
t=0
for i in a:
t+=int(i)
return t

min=abs(xuli(b[0])/3-t)
max=xuli(b[0])
for i in b:
if len(i)==3 and abs(xuli(i)/3-t)<min and xuli(i)>max:
min=abs(xuli(i)/3-t)
max=xuli(i)

print(max)