---

import sys
from math import isqrt

n, k = map(int, sys.stdin.read().split()[:2])
t = (isqrt(8 * k + 1) - 1) // 2
while t * (t + 1) // 2 > k:
    t -= 1
while (t + 1) * (t + 2) // 2 <= k:
    t += 1
print(min(n, t))