#include<bits/stdc++.h>

using namespace std;

int main()
{
	int n,k,ans = 0;cin >> n >> k;
	vector<int> v;
	for(int i = 0; i < n; ++i)
	{
		int j;cin >> j;
		v.push_back(j);
	}
	
	for(int i = 0; i < n; ++i)
	{
		if(v[i] + v[i+1] > k)
		{
			int j = v[i] + v[i + 1] k;
	  		ans += j;
			v[i+1] -= j; 
		}
	}
	cout << ans;
	
	return 0;	
}

我是忽略了什么条件吗?