ABC 338

void solve() {
    ll n, m;
    cin >> n >> m;
    vll x(m);
    rep(i, m) {
        cin >> x[i];
        x[i]--;
    }

    vll cumsum(n * 2 + 1, 0);

    rep(i, m - 1) {
        ll mi = min(x[i], x[i + 1]);
        ll mx = max(x[i], x[i + 1]);

        ll dr = mx - mi;
        ll dl = n - dr;
        cumsum[mi] += dl;
        cumsum[mx] -= dl;
        cumsum[0] += dr;
        cumsum[mi] -= dr;
        cumsum[mx] += dr;
        cumsum[n] -= dr;
    }

    rep(i, n * 2) cumsum[i + 1] += cumsum[i];

    ll ans = INF;
    rep(i, n) chmin(ans, cumsum[i]);
    cout << ans << endl;
}