from bisect import bisect_left as bl

M = 2 * 10**6
r = [i * i for i in range(M)]
D = int(input())
ans = M + 10
for x in range(M):
    p = bl(r, D - x * x)
    yy1 = r[p - 1]
    yy2 = r[p]
    yy3 = r[p + 1]
    wk = min(abs(D - x * x - yy1), abs(D - x * x - yy2), abs(D - x * x - yy3))
    ans = min(ans, wk)
print(ans)