#include<stdio.h>
long long int a[200005];
int main()
{
	long long int n, m;
	scanf("%lld %lld", &n, &m);
	long long int i;
	for (i = 0; i < n; i++)
		scanf("%lld", &a[i]);
	long long int min, mid, max;
	min = -1;
	max = 1e9 + 10;
	long long int cnt, f;
	while (max - min > 1)
	{
		mid = (max + min) / 2;
		cnt = f = 0;
		for (i = 0; i < n; i++)
		{
			if (a[i] + cnt < mid * m)
			{
				f++;
				break;
			}
			else
				cnt = a[i] + cnt - mid * m;
		}
		if (f > 0)
			max = mid;
		else
			min = mid;
	}
	printf("%lld\n", min);
	return 0;
}