#include <iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<cstdlib>
//#include<queue>
using namespace std;

long long a[200005];
long long n, x;
long long sum1 = 0, sum2 = 0;
int main() {
	cin >> n>>x;//输入个数
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i];
		//sum1 += a[i];
	}
	if (a[1] > x)
	{
		sum2 += a[1] - x;
		a[1] = x;
	}
	

	for (int i = 2; i <= n; i++)
	{
		if (a[i] > x - a[i - 1])
		{
			sum2 += a[i] + a[i - 1] - x;
			a[i] = x - a[i - 1];

		}
	}
	cout << sum2 << endl;
	return 0;
}

第一个是声明为long long 类型 第二个是看一下开的a数组是否够大，我就是不够大