N, M = map(int, input().split())
ok = 0
ng = 10**50
if N * ng * ng < (M + ng) * (M + ng):
    print("NaN")
    exit(0)
while ok + 1 < ng:
    mid = (ok + ng) // 2
    if N * mid * mid < (M + mid) * (M + mid):
        ok = mid
    else:
        ng = mid
print(M + ok)