INF = 10 ** 9
import sys
sys.setrecursionlimit(100000000)
dy = (-1,0,1,0)
dx = (0,1,0,-1)
from  collections import deque

def main():
    a,b,c = map(int,input().split())
    if b - c >= 0:
        ans = a + 10 * (b - c)
    elif a >= 10 * (c - b):
        ans = a - 10 * (c - b)
    elif a + b - 1 + 9 < c:
        ans = 'Impossible'
    else:
        if b > 0:
            ans = INF
            for i in range(a + 10):
                tot = i + 10 * (c - i)
                if tot <= a + 10 * b:
                    ans = min(ans,a + 10 * b - tot)
        else:
            if a <= c:
                ans = 'Impossible'
            else:
                ans = a - c
            
    print(ans)
if __name__ == '__main__':
    main()