a,b,c=map(int,input().split())

def eval(i: int) ->int:
  res = (10 * (c-i) + i) - (10 * b + a)
  return res

res = eval(0)
for i in range(1,c+1):
  eva=eval(i)
  if res < eva:
    res=eva

if res >=0 :
  print("Impossible")
else:
  print(abs(res))