static int M = 4;
static int[] a= new int[]{1,2,3,4,5,6};
static int[] b = new int[M];
static int N = a.length;
static List<String> list=new ArrayList<>();
static void C(int m,int n){
int i,j;
for(i=n;i<=m;i++) {
b[n-1] = i-1;
if(n>1) {
C(i - 1, n - 1);
}else {
List<String> op= new ArrayList<>();
for(j=0;j<=M-1;j++){
op.add(a[b[j]]+"");
System.out.print(a[b[j]] + " ");
}
String s = String.join(",", op);
list.add(s);
System.out.println();
}
}
}
public static void main(String[] args) {
C(N,M);
System.out.println(list.get(0));
System.out.println(list.size());
}