#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();
#define rd(v) int v=0;{int _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}

#define wt_rev(v) {long _z=v;do*--wp=_z%10+48;while(_z/=10);}

#define rep(v,e) for(int v=0;v<e;++v)
#define rep3(v,s,e) for(int v=s;v<e;++v)
#define min(a,b) (a<=b?a:b)
#define max(a,b) (a>=b?a:b)
#define chmax(v,a) (v=max(v,a))

void radix_sort_aux(unsigned*a,unsigned*b,int n){
	int c[256];
	for(int i=0;i<256;++i){
		c[i]=0;
	}
	for(int i=0;i<n;++i){
		++c[a[i]&255];
	}
	int t=0;
	for(int i=0;i<256;++i){
		int u=c[i];
		c[i]=t;
		t+=u;
	}
	for(int i=0;i<n;++i){
		b[c[a[i]&255]++]=a[i]>>8|a[i]<<24;
	}
}

void radix_sort(unsigned*a,int n){
	radix_sort_aux(a,a+n,n);
	radix_sort_aux(a+n,a,n);
	radix_sort_aux(a,a+n,n);
	radix_sort_aux(a+n,a,n);
}

int a[3004*2];
int dp[3][3001];

main(){
	char*rp=mmap(0l,1l<<25,1,2,0,0ll);

	rd(n);
	rd(m); ++m;
	rep(i,n){
		rd(ai);
		a[i]=ai;
	}
	radix_sort(a,n);

	int j0=0,j1=1,j2=2;
	rep(i,n-1){
		{ int t=j0; j0=j1; j1=j2; j2=t; }
		int a1=a[i+1];
		int a1a0=min(m,a1-a[i]);
		int k=0;
		for(;k<a1a0;++k){
			dp[j2][k]=dp[j1][k];
		}
		for(;k<m;++k){
			dp[j2][k]=max(dp[j1][k],dp[j0][k-a1a0]+a1);
		}
	}
	int res=0;
	rep(k,m){
		chmax(res,dp[j2][k]);
	}

	char wbuf[64],*wp=wbuf+sizeof wbuf;
	wt_rev(res);
	write(1,wp,wbuf+sizeof wbuf-wp);
	_exit(0);
}