#include <bits/stdc++.h>

using i64 = std::int64_t;

int main() {
    int N;
    std::cin >> N;
    std::vector<int> A(N);
    for (auto &e : A) std::cin >> e;

    i64 ans = 0;
    {
        i64 sum = 0;
        for (int i = 0; i < N; ++i) {
            sum += A[i] % A[(i + 1) % N];
        }
        ans = std::max(ans, sum);
    }
    {
        i64 baseScore = ans;
        for (int i = 1; i < N - 1; ++i) {
            i64 diff = -(A[i - 1] % A[i]) + -(A[i] % A[i + 1]);
            diff += A[i - 1] % A[i + 1];
            diff -= A[N - 1] % A[0];
            diff += A[N - 1] % A[i];
            diff += A[i] % A[0];
            ans = std::max(ans, baseScore + diff);
        }
    }
    std::cout << ans << std::endl;
}