代码如下:

#include <bits/stdc++.h>
#define int long long
using namespace std;

int a[100010];
void scand(int &num){
	int f=1,x=0;
	char c=getchar();
	while(c=='-'){
		f=-f,c=getchar();
	}
	while(c<'0' || c>'9'){
		c=getchar();
	}
	while('0'<=c && c<='9'){
		x=(x<<3)+(x<<1)+(c^48),c=getchar();
	}
	num=f*x;
}
void scand(int &num,int &num2){
	scand(num),scand(num2);
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n,k,sum=0;
	scand(n,k);
	for(int i=1;i<=n;i++){
		scand(a[i]);
	}
	for(int a=1;a<=n;a++){
		for(int b=a;b<=n;b++){
			int c[5]={0,k-a-b,2*k-a-b,3*k-a-b,0};
			for(int i=1;i<=3;i++){
				sum=max(sum,c[i]+a+b);
			}
		}
	}
	cout << sum;
	return 0;
}