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

#define rd(v) long v=0;{long _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}
#define wt(v) {ulong _z=v;do*--wp=_z%10+48;while(_z/=10);}
#define rep(v,e) for(long v=0;v<e;++v)
#define rrep(v,e) for(long v=e;v--;)

typedef unsigned long ulong;
char*mmap();

int a[10000];
ulong kp[65];

int main(){
	char*rp=mmap(0l,1l<<25,1,2,0,0ll);
	rd(n);
	rd(k);
	if(n>10000||k>1000){
		exit(1);
	}
	kp[1]=1;
	rep(i,n){
		rd(ai);
		a[i]=ai;
		ulong q=ai/64;
		ulong r=ai%64;
		if(r){
			rrep(j,32){
				kp[j+q+1]|=kp[j+1]<<r|kp[j]>>64-r;
			}
		}
		else{
			rrep(j,32){
				kp[j+q+1]|=kp[j+1];
			}
		}
	}
	if(!(kp[k/64+1]&1l<<k%64)){
		write(1,"-1",2);
	}
	else{
		long z=0;
		rep(i,n){
			ulong j=k+a[i];
			if(!(kp[j/64+1]&1l<<j%64)){
				z+=1;
			}
		}
		char wbuf[64],*wp=wbuf+sizeof wbuf;
		wt(z);
		write(1,wp,wbuf+sizeof wbuf-wp);
	}
	_exit(0);
}