import sys
input = sys.stdin.readline

n, m = map(int, input().split())
a = list(map(int, input().split()))

ok = 0
ng = 10 ** 9 + 1
while(abs(ok - ng) > 1):
    def func(mid):
        s = 0
        t = mid * m
        for i in range(n):
            s += a[i]
            if(s < t * (i + 1)):
                return False
        return True
    mid = (ok + ng) // 2
    if func(mid):
        ok = mid
    else:
        ng = mid
print(ok)