#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)

using namespace std;

using ll = long long;

int main() {
	int N; cin >> N;
	vector<int> A(N);
	rep (i, N) cin >> A[i];
	ll ans = 0;
	rep (i, N) ans += A[i] % A[(i + 1) % N];
	ll mx = 0;
	rep (i, N) mx = max<ll>(mx, A[N - 1] % A[i] + A[i] % A[0] - A[i] - A[N - 1] % A[0]);
	cout << ans + mx << endl;
}