#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    vector<int> a(n, 0);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    ll ans = 0;
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            ans += abs(a[i] % a[j] - a[j] % a[i]);
        }
    }
    cout << ans << endl;
}