def solve():
# all hexagonal numbers are also triangle
return next(n for n in set(pentagonal(100000)) & set(hexagonal(100000))
if n > 40755)
def solve():
l = list(pentagonal(10000))
s = set(l)
return next(m - n for n in l for m in l
if m - n in s
if m + n in s)
def solve():
l = list(pentagonal(10000))
s = set(l)
return next(m - n for n in l for m in l if m - n in s if m + n in s)