# increase
# 10 buy 1 +9

# decrease
# 1*10 exchange 10 -9

# if A+B==C and B>0 then 10 buy 9


def same(A, B, diff):
    if B > 0:
        return 9
    return 0


def increase(A, B, diff):
    if B == 0:
        return 0
    if diff > 9:
        return 0
    return 10-diff


def decrease(A, B, diff):
    cnt = 0
    while diff < -9:
        if A > 9:
            A -= 10
            B += 1
            diff += 9
    if diff == 0:
        return same(A, B, diff)
    if A+diff > 0:
        return cnt-diff
    cnt += A
    diff += A
    if B+diff > 0:
        return cnt-diff*10
    return 0


A, B, C = [int(i) for i in input().split()]
diff = C-A-B
if diff > 0:
    price = increase(A, B, diff)
elif diff < 0:
    price = decrease(A, B, diff)
else:
    price = same(A, B, diff)

if price > 0:
    print(price, '\n')
else:
    print("Impossible\n")