#include <bits/stdc++.h>
using namespace std;
using lint = long long;
struct fast_ios { fast_ios(){ cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)

// Sieve of Eratosthenes
// (*this)[i] = (divisor of i, greater than 1)
// Example: [0, 1, 2, 3, 2, 5, 3, 7, 2, 3, 2, 11, ...]
// Complexity: Space O(MAXN), Time (construction) O(MAXNloglogMAXN)
struct SieveOfEratosthenes : std::vector<int>
{
    std::vector<int> primes;
    SieveOfEratosthenes(int MAXN) : std::vector<int>(MAXN + 1) {
        std::iota(begin(), end(), 0);
        for (int i = 2; i <= MAXN; i++) {
            if ((*this)[i] == i) {
                primes.push_back(i);
                for (int j = i; j <= MAXN; j += i) (*this)[j] = i;
            }
        }
    }
    using T = long long int;
    // Prime factorization for x <= MAXN^2
    // Complexity: O(log x)          (x <= MAXN)
    //             O(MAXN / logMAXN) (MAXN < x <= MAXN^2)
    std::map<T, int> Factorize(T x) {
        assert(x <= 1LL * (int(size()) - 1) * (int(size()) - 1));
        std::map<T, int> ret;
        if (x < int(size())) {
            while (x > 1) {
                ret[(*this)[x]]++;
                x /= (*this)[x];
            }
        }
        else {
            for (auto p : primes) {
                while (!(x % p)) x /= p, ret[p]++;
                if (x == 1) break;
            }
            if (x > 1) ret[x]++;
        }
        return ret;
    }
    std::vector<T> Divisors(T x) {
        std::vector<T> ret{1};
        for (auto p : Factorize(x)) {
            int n = ret.size();
            for (int i = 0; i < n; i++) {
                for (T a = 1, d = 1; d <= p.second; d++) {
                    a *= p.first;
                    ret.push_back(ret[i] * a);
                }
            }
        }
        return ret; // Not sorted
    }
};
SieveOfEratosthenes sieve(1000010);

int main()
{
    int N, M;
    cin >> N >> M;
    vector<int> A(M);
    for (auto &a : A) cin >> a;
    lint ret = -accumulate(ALL(A), 0LL);

    constexpr int L = 1e6 + 10;
    vector<int> Phi(L + 1);
    iota(ALL(Phi), 0);
    FOR(p, 2, L + 1) {
        if (Phi[p] == p) {
            Phi[p] = p - 1;
            for (int i = p * 2; i <= L; i += p) {
                Phi[i] = Phi[i] / p * (p - 1);
            }
        }
    }

    vector<lint> memo(L + 1, -1);
    for (auto a : A) {
        lint ans = memo[a];
        if (ans < 0) {
            ans = 0;
            auto v = sieve.Divisors(a);
            for (auto d : v) ans += d * Phi[a / d];
        }
        memo[a] = ans;
        ret += ans;
    }
    cout << ret << '\n';
}