// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)n; ++i)
#define rrep(i, n) for (int i = (int)n - 1; i >= 0; --i)
#define ALL(v) v.begin(), v.end()
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
const array<int, 8> di = {0, 1, 0, -1, 1, 1, -1, -1}, dj = {1, 0, -1, 0, 1, -1, -1, 1};
const array<string, 2> YESNO = {"NO", "YES"};
const array<string, 2> YesNo = {"No", "Yes"};
const array<string, 2> yesno = {"no", "yes"};
void YES(bool b = true) { cout << YESNO[b] << '\n'; }
void Yes(bool b = true) { cout << YesNo[b] << '\n'; }
void yes(bool b = true) { cout << yesno[b] << '\n'; }
template<typename T, typename U>
inline bool chmax(T& a, const U& b) {
    if (a < b){
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U>
inline bool chmin(T& a, const U& b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<typename T>
T MAX(const vector<T>& v) { return *max_element(v.begin(), v.end()); }
template<typename T>
T MIN(const vector<T>& v) { return *min_element(v.begin(), v.end()); }
template<typename T>
T SUM(const vector<T>& v) { return accumulate(v.begin(), v.end(), T()); }
template<typename T>
void UNIQUE(vector<T>& v) {
    sort(v.begin(), v.end());
    v.erase(unique(v.begin(), v.end()), v.end());
}
template<typename T>
T POW(T a, int n) {
    T res = 1;
    for (; n > 0; n >>= 1, a *= a) if (n & 1) res *= a;
    return res;
}
template<typename T>
int lb(const vector<T>& v, T x) {
    return distance(v.begin(), lower_bound(v.begin(), v.end(), x));
}
template<typename T>
int ub(const vector<T>& v, T x) {
    return distance(v.begin(), upper_bound(v.begin(), v.end(), x));
}
/**
 * @brief 多次元 vector の作成
 * @author えびちゃん
 */
namespace detail {
    template<typename T, int N>
    auto make_vec(vector<int>& sizes, T const& x) {
        if constexpr (N == 1) {
            return vector(sizes[0], x);
        } else {
            int size = sizes[N-1];
            sizes.pop_back();
            return vector(size, make_vec<T, N-1>(sizes, x));
        }
    }
}
template<typename T, int N>
auto make_vec(int const(&sizes)[N], T const& x = T()) {
    vector<int> s(N);
    for (int i = 0; i < N; ++i) s[i] = sizes[N-i-1];
    return detail::make_vec<T, N>(s, x);
}
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    for (auto it = v.begin(); it != v.end(); ++it) {
        if (it == v.begin()) os << *it;
        else os << ' ' << *it;
    }
    return os;
}
template<typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << p.first << ' ' << p.second;
    return os;
}
__attribute__((constructor))
void setup() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
}
// #include <atcoder/all>
// using namespace atcoder;
// using mint = modint1000000007;
// using mint = modint998244353;

int main() {
    ll n, x;
    cin >> n >> x;
    vector<ll> s(n);
    rep(i, n) cin >> s[i];
    ll ans = n*x - SUM(s);
    ans = x - ans;
    cout << ans << '\n';
}