INF = 1001001001

A, B, C = map(int, input().split())

budget = A + 10 * B
mi = INF
for a in range(min(C+1, A+10)):
    b = C - a
    bought = budget - (a + 10 * b)
    if bought > 0:
        mi = min(mi, bought)

print('Impossible' if mi == INF else mi)