#include <iostream>

using namespace std;

int main() {
  int a, b, c;
  int answer = 0;
  cin >> a >> b >> c;
  if (b >= c) answer = 10 * (b-c) + a;
  else if (a + b < c) answer = -1;
  else {
    int k = (a - (c-b)) / 10;
    int l = a - 10*k;
    answer = l - (c - b - k);
  }
  if (answer <= 0) cout << "Impossible" << endl;
  else cout << answer  << endl;

  return 0;
}