a,b,c = map(int,input().split())
t = a + 10*b
for i in range(c+1):
    v = i + 10*(c-i)
    if v > t: continue
    k = (t-v+9)//10
    if c-i+k >= b and t-v:
        print(t-v)
        exit()
print("Impossible")