#include <iostream>
using namespace std;

int main() {
    int a, b, c;
    cin >> a >> b >> c;
    int price = 0;
    int rest = a+b;
    if (rest-c <= 0) {
        cout << "Impossible" << endl;
        return 0;
    }
    while (rest>c) {
        if (rest>b) price += 1;
        else price += 10;
        rest--;
    }
    cout << price << endl;
    return 0;
}