Codeforces Round #256 (Div. 2)——Painting Fence

const int maxn = 51000;

int h[maxn], n;

int fun(int l, int r, int sub)
{
    if (l > r) return 0;
    int Min = INF, id;
    FE(i, l, r)
        if (h[i] < Min)
        {
            Min = h[i];
            id = i;
        }
    return min(r - l + 1, fun(l, id - 1, Min) + fun(id + 1, r, Min) + Min - sub);
}

int main()
{
    while (~RI(n))
    {
        FE(i, 1, n)
            RI(h[i]);
        cout << fun(1, n, 0) << endl;
    }
    return 0;
}