using namespace std;
const int maxn=1e7;
long long int arr[maxn];
int main()
{
   long long int n;
    long long m;
    cin>>n>>m;
    for(long long int i=1;i<=n;i++){
        cin>>arr[i];
    }
    long long sum1=0,sum2=0;
    for(long long int i=1;i<n;i++){
        if(arr[i]+arr[i+1]>m){
            sum1+=(arr[i]+arr[i+1]-m);
            arr[i+1]=m-arr[i];
        }    
    }
    for(long long int i=2;i<=n;i++){
        if(arr[i]+arr[i-1]>m){
            sum2+=(arr[i]+arr[i-1]-m);
            arr[i-1]=m-arr[i];
        }    
    }
    if(sum1<=sum2)cout<<sum1<<endl;
    else cout<<sum2<<endl;
    return 0;
}```