N = int(input()) L = list(map(int, input().split())) K = int(input()) # 長さ m の棒を K 本作れるか def can(m: float) -> bool: cnt = 0 for l in L: cnt += int(l / m) return cnt >= K lo = 0 hi = max(L) ans = lo for _ in range(60): m = (lo + hi) / 2 if can(m): ans = max(ans, m) lo = m else: hi = m print(ans) #print(f'{ans:.10f}')