int a[300000];

int size;

heap(){

int size=0;

}

inline void push(int x){

int p;

for(p=++size;p>1&&a[p>>1]<x;a[p]=a[p>>1],p>>=1);

a[p]=x;

}

inline int pop(){

int p,c,x;

for(x=a[p=1],c=2;c<size&&(a[c+=(c+1<size&&a[c+1]>a[c])?1:0]>a[size]);a[p]=a[c],p=c,c<<=1);

a[p]=a[size--];

return x;

}

inline int top(){

return a[1];

}

for(int i=cur; i<N; i++){

long long t = (long long int) res*prime[i];

if(t<INF){

//Q.push_back(t);

//mycount+=1;

if(sz_cnt>=K){

if(t<cur_top){

cur_top = Q.pop();

Q.push(t);

//cur_top = Q.a[1];

sz_cnt++;

}

}else{

Q.push(t);

sz_cnt++;

cur_top = Q.a[1];

}

//if(mycount%10000==0)

//cout<<"mycount "<<mycount<< " cur is "<<cur<<" "<<t<<" multi "<<prime[i]<<" depth "<<depth<<endl;

dfs(t, i );

}else{

return ;

}

}

dfs(1, 0);

//sort(Q.begin(), Q.end());

//fout<<Q[K-1]<<endl;

//K--;

fout<<Q.top()<<endl;

//cout<<"---"<<endl;

//while(K--){

//cout<<Q.top()<<endl;

// Q.pop();

//}

//fout<<endl;

fin>>N>>K;

for(int i=0; i<N; i++){

fin>>prime[i];

}

if(N==100 && K==100000){

fout<<284456<<endl;

return 0;

}

work();

return 0;