def issq(x):
    sqr = int(x ** 0.5)
    if sqr ** 2 == x:
        return True
    return False

def con_frac(num):
    a, b = 0, 1
    para = []
    while b and (a, b) not in para:
        d = int((num ** 0.5 + a) / b)
        yield d
        para.append((a, b))
        a = b * d - a
        b = (num - a ** 2) // b

def con2frac(con_list):
    a, b = 1, 0
    for r in reversed(con_list):
        a, b = b + a * r, a
    return a, b

def solve(d):
    x, y = con2frac(list(con_frac(d))[:-1])
    if x ** 2 - d * y ** 2 == 1:
        return (x, y)
    else:
        return (2 * x * y, x ** 2 + d * y ** 2)

def search(limit):
    for num in range(2, limit + 1):
        yield solve(num)[1], num

print(max(search(1000))[1])