def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    
    N = int(data[0])
    K = int(data[1])
    A = list(map(int, data[2:2+N]))
    
    if K == 1:
        print(sum(A))
        return
    
    B = A + A
    prefix = [0] * (2 * N + 1)
    for i in range(2 * N):
        prefix[i+1] = prefix[i] + B[i]
    
    total = sum(A)
    low = 0
    high = total // K
    ans = 0
    
    while low <= high:
        mid = (low + high) // 2
        if mid == 0:
            ans = mid
            low = mid + 1
            continue
        if total < K * mid:
            high = mid - 1
            continue
        
        next_j = [0] * (2 * N)
        right = 0
        for i in range(2 * N):
            while right < 2 * N and prefix[right + 1] - prefix[i] < mid:
                right += 1
            if right >= 2 * N:
                next_j[i] = 2 * N
            else:
                next_j[i] = right
        
        found = False
        for s in range(N):
            current = s
            count = 0
            end = s + N - 1
            while current <= end:
                if next_j[current] > end:
                    break
                count += 1
                if count >= K:
                    found = True
                    break
                current = next_j[current] + 1
            if found:
                break
        
        if found:
            ans = mid
            low = mid + 1
        else:
            high = mid - 1
    
    print(ans)

if __name__ == '__main__':
    main()