#pragma region template /* template made by nouka28 last update 2024.7.7 */ //include #include using namespace std; //atcoder #include using namespace atcoder; using mint=atcoder::modint998244353; // using mint=atcoder::modint1000000007; // using mint=atcoder::modint; istream& operator>>(istream&is,mint &x){long long x_;is>>x_;x=x_;return is;} ostream& operator<<(ostream&os,mint &x){os<>(i)&1) //using using u32=unsigned int; using u64=unsigned long long; using ull=unsigned long long; using i32=signed int; using i64=signed long long; using ll=signed long long; using f64=double; using f80=long double; using pi=pair; using pl=pair; using pd=pair; templateusing V=vector; templateusing VV=V>; templateusing VVV=V>>; templateusing VVVV=V>>>; templateusing VVVVV=V>>>>; templateusing pqmax=priority_queue; templateusing pqmin=priority_queue,greater>; using u128=__uint128_t; using i128=__int128_t; //io INT128 i128 i128_parse(string &s){i128 ret=0;for(i32 i=0;i<(i32)s.length();i++)if('0'<=s[i]&&s[i]<='9')ret=10*ret+s[i]-'0';return ret;} u128 u128_parse(string &s){u128 ret=0;for(i32 i=0;i<(i32)s.length();i++)if('0'<=s[i]&&s[i]<='9')ret=10*ret+s[i]-'0';return ret;} istream &operator>>(istream &is,i128 &x){string s;is>>s;x=i128_parse(s);return is;} istream &operator>>(istream &is,u128 &x){string s;is>>s;x=u128_parse(s);return is;} ostream &operator<<(ostream &os,i128 x){ ostream::sentry s(os); if(s){u128 tmp=x<0?-x:x;char buffer[128];char *d=end(buffer); do{--d;*d="0123456789"[tmp%10];tmp/=10;}while(tmp!=0); if(x<0){--d;*d='-';} int len=end(buffer)-d; if (os.rdbuf()->sputn(d,len)!=len){os.setstate(ios_base::badbit);} } return os; } //const const i64 LINF=0x1fffffffffffffff; const i32 INF=0x3fffffff; const i64 MOD=998244353; const i64 MOD2=1000000007; const f80 PI=3.1415926535897932384626433832795028841971; const f80 DINF=numeric_limits::infinity(); const f80 EPS=1e-9; const i64 di[]={0,1,0,-1,1,-1,1,-1}; const i64 dj[]={1,0,-1,0,1,1,-1,-1}; //function #define overload4(_1,_2,_3,_4,name,...) name #define overload3(_1,_2,_3,name,...) name #define rep1(n) for(i64 i=0;i(a);) #define rrep4(i,a,b,c) for(i64 i=(a)+((b)-(a)-1)/(c)*(c)i>=a;i-=c) #define rrep(...) overload4(__VA_ARGS__,rrep4,rrep3,rrep2,rrep1)(__VA_ARGS__) #define SUM(...) accumulate(ALL(__VA_ARGS__),i64(0)) #define DSUM(...) accumulate(ALL(__VA_ARGS__),f80(0)) templatebool chmin(T &x,const T&y){if(x>y){x=y;return true;}return false;} templatebool chmax(T &x,const T&y){if(xi32 lob(const V&arr,const T&v){return (i32)(lower_bound(ALL(arr),v)-arr.begin());} templatei32 upb(const V&arr,const T&v){return (i32)(upper_bound(ALL(arr),v)-arr.begin());} templateconstexpr auto min(T a,T b,T c){return min(a,min(b,c));} templateconstexpr auto min(T... a){return min(initializer_list>{a...});} templateconstexpr auto max(T a,T b,T c){return max(a,max(b,c));} templateconstexpr auto max(T... a){return max(initializer_list>{a...});} //io struct SetUpIO{ SetUpIO(){ ios::sync_with_stdio(false); cin.tie(nullptr); cout<>x;} void scan(u32&x){cin>>x;} void scan(u64 &x){cin>>x;} void scan(i32 &x){cin>>x;} void scan(i64 &x){cin>>x;} void scan(string &x){cin>>x;} void scan(mint &x){cin>>x;} templatevoid scan(pair &x){scan(x.first);scan(x.second);} templatevoid scan(V &x){for(T &ele:x){scan(ele);}} templatevoid scan(deque &x){for(T &ele:x){scan(ele);}} templatevoid scan(array &x){for(T &ele:x){scan(ele);}} templatevoid scan(T (&x)[size]){for(T &ele:x){scan(ele);}} void rd(){} templatevoid rd(Head &head,Tail &...tail){scan(head);rd(tail...);} #define CHR(...) char __VA_ARGS__;rd(__VA_ARGS__) #define U32(...) u32 __VA_ARGS__;rd(__VA_ARGS__) #define U64(...) u64 __VA_ARGS__;rd(__VA_ARGS__) #define I32(...) i32 __VA_ARGS__;rd(__VA_ARGS__) #define I64(...) i64 __VA_ARGS__;rd(__VA_ARGS__) #define UINT(...) u32 __VA_ARGS__;rd(__VA_ARGS__) #define ULL(...) u64 __VA_ARGS__;rd(__VA_ARGS__) #define INT(...) i32 __VA_ARGS__;rd(__VA_ARGS__) #define LL(...) i64 __VA_ARGS__;rd(__VA_ARGS__) #define STR(...) string __VA_ARGS__;rd(__VA_ARGS__) #define VEC(type,name,size) V name(size);rd(name); #define VVEC(type,name,size1,size2) VV name(size1,V(size2));rd(name) //out void print(){putchar(' ');} void print(bool x){printf("%d",x);} void print(u32 x){printf("%u",x);} void print(u64 x){printf("%llu",x);} void print(i32 x){printf("%d",x);} void print(i64 x){printf("%lld",x);} void print(char x){printf("%c",x);} void print(f64 x){printf("%.15f",x);} void print(f80 x){printf("%.15Lf",x);} void print(const string &x){for(auto&&i:x)print(i);} void print(mint x){printf("%d",x.val());} templatevoid print(const V&); templatevoid print(const pair&x){print(x.first);putchar(' ');print(x.second);} templatevoid print(complex&x){if(x.real()>=0)print('+');print(x.real());if(x.imag()>=0)print('+');print(x.imag());print('i');} templatevoid print(const V&x){if(x.empty())return;print(x[0]);for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} templatevoid print(const deque&x){if(x.empty())return;print(x[0]);for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} templatevoid print(const set&x){if(x.empty())return;print(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} templatevoid print(const unordered_set&x){if(x.empty())return;print(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} templatevoid print(const multiset&x){if(x.empty())return;print(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} templatevoid print(const unordered_multiset&x){if(x.empty())return;print(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} templatevoid print(map&x){if(x.empty())return;print(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} templatevoid print(unordered_map&x){if(x.empty())return;print(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(' ');print(*i);}} template void print(const array& x){ print(x[0]); for(auto i = x.begin(); ++i != x.end(); ){ putchar(' '); print(*i); } } templatevoid print(const T(&x)[size]){print(x[0]);for(auto i=x;++i!=end(x);){/*putchar(' ');*/print(*i);}} templatevoid print(const T&a){cout<int out(const T&t){print(t);putchar('\n');return 0;} templateint out(const Head&head,const Tail&...tail){print(head);putchar(' ');out(tail...);return 0;} #ifdef LOCAL void dbg(){putchar(' ');} void dbg(bool x){printf("%d",x);} void dbg(u32 x){printf("%u",x);} void dbg(u64 x){printf("%llu",x);} void dbg(i32 x){printf("%d",x);} void dbg(i64 x){printf("%lld",x);} void dbg(char x){printf("%c",x);} void dbg(f64 x){printf("%.15f",x);} void dbg(f80 x){printf("%.15Lf",x);} void dbg(const string &x){for(auto&&i:x)dbg(i);} void dbg(mint x){printf("%d",x.val());} templatevoid dbg(const V&); templatevoid dbg(const pair&x){putchar('(');dbg(x.first);putchar(',');dbg(x.second);putchar(')');} templatevoid dbg(complex&x){if(x.real()>=0)dbg('+');dbg(x.real());if(x.imag()>=0)dbg('+');dbg(x.imag());dbg('i');} templatevoid dbg(const V&x){putchar('[');if(!x.empty()){dbg(x[0]);for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar(']');} templatevoid dbg(const deque&x){putchar('[');if(!x.empty()){dbg(x[0]);for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar(']');} templatevoid dbg(const set&x){putchar('{');if(!x.empty()){dbg(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar('}');} templatevoid dbg(const unordered_set&x){putchar('{');if(!x.empty()){dbg(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar('}');} templatevoid dbg(const multiset&x){putchar('{');if(!x.empty()){dbg(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar('}');} templatevoid dbg(const unordered_multiset&x){putchar('{');if(!x.empty()){dbg(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar('}');} templatevoid dbg(map&x){putchar('{');if(!x.empty()){dbg(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar('}');} templatevoid dbg(unordered_map&x){putchar('{');if(!x.empty()){dbg(*x.begin());for(auto i=x.begin();++i!=x.end();){putchar(',');dbg(*i);}}putchar('}');} template void dbg(const array& x){ putchar('[');dbg(x[0]); for(auto i = x.begin(); ++i != x.end(); ){ putchar(','); dbg(*i); } putchar(']');} templatevoid dbg(const T(&x)[size]){/*putchar('[');*/dbg(x[0]);for(auto i=x;++i!=end(x);){/*putchar(' ')*/;dbg(*i);}/*putchar(']');*/} templatevoid dbg(const T&a){cout<int dbg2(const T&t){dbg(t);putchar('\n');return 0;} templateint dbg2(const Head&head,const Tail&...tail){dbg(head);putchar(' ');dbg2(tail...);return 0;} #define debug(...) {dbg((string)(#__VA_ARGS__));dbg(":");dbg2(__VA_ARGS__);} #else #define debug(...) void(0) #endif //random random_device rnd;mt19937 mt(rnd());const i64 MT_MAX=LINF; uniform_int_distribution RAND(0,MT_MAX); f64 randd(){return 1.0*RAND(mt)/MT_MAX;} //random value [a,b] i64 randint(i64 a,i64 b){return a+RAND(mt)%(b-a+1);} //funtion2 #define extrep(v,...) for(auto v:__MAKE_MAT__({__VA_ARGS__})) vector> __MAKE_MAT__(vector v){ if(v.empty())return vector>(1,vector()); i64 n=v.back();v.pop_back();vector> ret,tmp=__MAKE_MAT__(v); for(auto e:tmp)for(i64 i=0;i pair,vector> sortperm(vector v){ vector> sv; for(i32 i=0;i<(i32)v.size();i++){sv.push_back({v[i],i});} sort(sv.begin(),sv.end());vector rv;vector p; for(auto[x,idx]:sv){rv.push_back(x);p.push_back(idx);} return {rv,p}; } i64 pow(i64 a,i64 b){i64 x=1;while(b){if(b&1){x*=a;}a=a*a;b>>=1;}return x;} bool isupper(char x){return('A'<=x&&x<='Z');} bool islower(char x){return('a'<=x&&x<='z');} char upper(char &x){if(isupper(x)){return x;}return x-'a'+'A';} char lower(char &x){if(islower(x)){return x;}return x-'A'+'a';} string upper(string s){for(auto&e:s)e=upper(e);return s;} string lower(string s){for(auto&e:s)e=lower(e);return s;} bool isdigit(char x){return('0'<=x&&x<='9');} bool ingrid(int x,int y,int h,int w){return 0<=x&&x rd(0,MT_MAX); double randd(){ return 1.0*rd(mt)/MT_MAX; } long long randint(long long a,long long b){ // [a,b]の乱数を生成 return a+rd(mt)%(b-a+1); } template vector Quotients(T n){ vector retl,retr; for(int i=1;i*i<=n;i++){ retl.push_back(i); if(iT ceil_sqrt(T n){ T l=-1,r=n; while(r-l>1){ T m=(l+r)>>1; if(m*m>=n)r=m; else l=m; } return r; } //ceil(a/b) templateT ceil(T a,T b){ if(a>=0){ return (a+b-1)/b; }else{ return (a)/b; } }; //floor(a/b) templateT floor(T a,T b){ if(a>=0){ return a/b; }else{ return -(-a+b-1)/b; } }; //x^y mod m templateT modpow(T x,T y,T m){ T res=1%m;x%=m; while(y){ if(y%2)res=(res*x)%m; x=(x*x)%m; y>>=1; } return res; } //a^0+a^1+..+a^(n-1) (mod m) template T geometric_progression(T a,T n,T m){ if(n==0)return 0; if(n%2==1){ return (geometric_progression(a,n-1,m)*a+1)%m; }else{ return (geometric_progression(a*a%m,n/2,m)*(1+a))%m; } }; //素数判定(高速) bool is_prime(long long n){ if(n<=1)return 0; if(n==2)return 1; if(n%2==0)return 0; long long s=0,d=n-1; while(d%2==0)d/=2,s++; if(n<4759123141LL){ for(long long e:{2,7,61}){ if(n<=e)break; long long t,x=modpow<__int128_t>(e,d,n); if(x!=1){ for(t=0;t(e,d,n); if(x!=1){ for(t=0;t>19))^(tt^(tt>>8))); } //ロー法 Nを割り切る素数を見つける long long pollard(long long n){ if(n%2==0)return 2; if(is_prime(n))return n; long long step=0; while(true){ long long r=(long long)xor_shift_rng(); auto f=[&](long long x)->long long {return ((__int128_t(x)*x)%n+r)%n;}; long long x=++step,y=f(x); while(true){ long long p=gcd(abs(y-x),n); if(p==0||p==n)break; if(p!=1)return p; x=f(x); y=f(f(y)); } } } //internal fast factrize vector void _internal_factrize_vector(long long n,vector&v){ if(n==1)return; long long p=pollard(n); if(p==n){v.push_back(p);return;} _internal_factrize_vector(p,v); _internal_factrize_vector(n/p,v); } //fast factrize vector vector factrize_vector(long long n){ vector res; _internal_factrize_vector(n,res); sort(res.begin(),res.end()); return res; } //internal fast factrize map void _internal_factrize_map(long long n,map&v){ if(n==1)return; long long p=pollard(n); if(p==n){v[p]++;return;} _internal_factrize_map(p,v); _internal_factrize_map(n/p,v); } //fast factrize map map factrize_map(long long n){ map res; _internal_factrize_map(n,res); return res; } //fast factor vector factor(long long n){ map fm;_internal_factrize_map(n,fm); vector res={1}; for(auto[i,j]:fm){ vector tmp; int p=1; for(long long k=0;k<=j;k++){ for(auto e:res){ tmp.push_back(e*p); } p*=i; } swap(res,tmp); } return res; } //euler phi function long long euler_phi(long long n){ vector ps=factrize_vector(n); ps.erase(unique(ps.begin(),ps.end()),ps.end()); for(long long p:ps){ n/=p;n*=(p-1); } return n; } //ax+by=gcd(a,b) template tuple extgcd(T a,T b){ T x1=1,y1=0,d1=a,x2=0,y2=1,d2=b; while(d2!=0){ T q=d1/d2,u=d1-d2*q,v=x1-x2*q,w=y1-y2*q; d1=d2;d2=u;x1=x2;x2=v;y1=y2;y2=w; } if(d1<0){ d1=-d1;x1=-x1;y1=-y1; } return {d1,x1,y1}; } //x inverse (mod m) long long modinv(long long a,long long m){ long long b=m,u=1,v=0; while(b){ long long t=a/b; a-=t*b;swap(a,b); u-=t*v;swap(u,v); } u%=m; if(u<0)u+=m; return u; } //find primitive root long long primitive_root(long long p){ vector f=factrize_vector(p-1); f.erase(unique(f.begin(),f.end()),f.end()); while(1){ long long x=randint(1,p-1); bool flg=1; for(auto e:f)if(modpow<__int128_t>(x,(p-1)/e,p)==1){flg=0;break;} if(flg)return x; } } //x^k=y (mod m) gcd(x,m)=1 k>=0 long long discrete_logarithm_coprime_mod(long long x,long long y,long long m){ x%=m;y%=m; if(y==1||m==1){ return 0; } if(x==0){ if(y==0)return 1; else return -1; } long long M=ceil_sqrt(m),a=modpow(modinv(x,m),M,m); unordered_map mp; long long pow_x=1; for(long long i=0;i=1 long long discrete_Nlogarithm_coprime_mod(long long x,long long y,long long m){ if(m==1){ if(x==1)return 1; else return -1; } if(x==0){ if(y==0)return 1; else return -1; } long long M=ceil_sqrt(m),a=modpow(modinv(x,m),M,m); unordered_map mp; long long pow_x=1; for(long long i=0;i<=M;i++){ if(!mp.count(pow_x))mp[pow_x]=i; pow_x=pow_x*x%m; } long long ya=y; for(long long i=0;i0)return i*M; else if(mp.count(ya))return M*i+mp[ya]; ya=ya*a%m; } return -1; } //x^k=y (mod m) k>=0 long long discrete_logarithm_arbitrary_mod(long long x,long long y,long long m){ if(m==1){ return 0; } x%=m;y%=m; long long d,pow_x=1; for(d=0;;d++){ if(!(m>>d))break; if(pow_x==y){ return d; } pow_x=pow_x*x%m; } long long g=gcd(pow_x,m); if(y%g!=0){ return -1; } m/=g; long long z=y*modinv(pow_x,m),t=discrete_logarithm_coprime_mod(x,z,m); if(t==-1)return -1; else return d+t; } //x^k=y (mod m) k>=1 long long discrete_Nlogarithm_arbitrary_mod(long long x,long long y,long long m){ if(m==1){ if(x==1)return 1; else return -1; } x%=m;y%=m; long long d,pow_x=1; for(d=0;;d++){ if(!(m>>d))break; if(pow_x==y&&d){ return d; } pow_x=pow_x*x%m; } long long g=gcd(pow_x,m); if(y%g!=0){ return -1; } m/=g; long long z=y*modinv(pow_x,m),t; if(d)t=discrete_logarithm_coprime_mod(x,z,m); else t=discrete_Nlogarithm_coprime_mod(x,y,m); if(t==-1)return -1; else return d+t; } } int main(){ INT(n,m); VEC(int,a,n); sort(ALL(a)); set st; set ast(ALL(a)); rep(i,1,n){ auto ds=nouka28::factor(a[i]); debug(ds); bool f=0; for(auto&&e:ds){ if(st.count(e)){ f=1; } } if(f)continue; for(int j=a[i];j<=m;j+=a[i]){ if(!ast.count(j)){ out(-1); return 0; } } st.insert(a[i]); } out(LEN(st)); out(st); }