def main():
    import sys
    input = sys.stdin.read().split()
    N = int(input[0])
    K = int(input[1])
    A = list(map(int, input[2:2+N]))
    
    total = sum(A)
    max_A = max(A)
    
    if K == 1:
        print(total)
        return
    
    left = 1
    right = min(total // K, max_A)
    answer = 0
    
    def is_possible(M):
        if total < K * M:
            return False
        cnt = 0
        current = 0
        for num in A:
            current += num
            if current >= M:
                cnt += 1
                current = 0
        return cnt >= K or (cnt >= K-1 and current >= M)
    
    while left <= right:
        mid = (left + right) // 2
        if is_possible(mid):
            answer = mid
            left = mid + 1
        else:
            right = mid - 1
    
    print(answer)

if __name__ == "__main__":
    main()