ls = [tuple(map(int,input().split())) for _ in range(3)]

def extgcd(a, b):
    if b:
        d, y, x = extgcd(b, a % b)
        y -= (a // b) * x
        return d, x, y
    return a, 1, 0

# V = [(X_i, Y_i), ...]: X_i (mod Y_i)
def remainder(V):
    x = 0; d = 1
    for X, Y in V:
        g, a, b = extgcd(d, Y)
        if (X-x)%g:
            return -1,-1 # 理屈は分からんが駄目な時にこれを出力
        x, d = (Y*b*x + d*a*X) // g, d*(Y // g)
        x %= d
    if x == 0:
        return d,d
    return x, d # 数字≡x(mod d)ならいいという情報？　最小の数字はx

print(remainder(ls)[0])