#include<iostream>
using namespace std;
int main()
{
	int n,ans=0;
	long long x;
	cin>>n>>x;
	int a[100005];
	for(long long i=1;i<=n;i++)
	cin>>a[i];
	
	for(long long i=1;i<=n;i++)
	{
		while(a[i]>x)
		{
			a[i]--;
			ans++;
		 } 
		while(a[i]+a[i+1]>x)
		{
			a[i+1]--;
			ans++;
		}
	}
	cout<<ans<<endl;
	return 0;
 }