#include <iostream>

int main() {
    int n, x;
    int sum = 0;
    
    std::cin >> n >> x;
    for (int i = 0; i < n; i++) {
        int a;
        std::cin >> a;
        sum += (x - a);
    }
    std::cout << (x - sum) << std::endl;
    
    return 0;
}