![在这里插入图片描述](http://imgconvert.csdnimg.cn/aHR0cHM6Ly9pbWctYmxvZy5jc2RuaW1nLmNuLzIwMTkwNzMwMTgzMzE3NjIwLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3dhdGVybWFyayx0eXBlX1ptRnVaM3BvWlc1bmFHVnBkR2ssc2hhZG93XzEwLHRleHRfYUhSMGNITTZMeTlpYkc5bkxtTnpaRzR1Ym1WMEwyRXhORE01TnpjMU5USXcsc2l6ZV8xNixjb2xvcl9GRkZGRkYsdF83MA?x-oss-process=image/format,png)
import java.util.Scanner;
public class Main {
private static Scanner cin;
private static int[] numbers ;
private static int counter = 0;
public static void main(String args[]) throws Exception {
cin = new Scanner(System.in);
int n = cin.nextInt();
int k = cin.nextInt();
numbers = new int[n];
for(int i=0;i<n;i++) {
numbers[i] = cin.nextInt();
}
for(int i=0;i<n-k+1;i++) {
Main.calc(n,i,k,0,String.valueOf(i));
}
System.out.println(counter);
}
public static void calc(int n,int start, int k,int ret,String value) {
int sum = 0;
if(n-start <k ) {
return;
}
if (k == 1) {
sum = ret + numbers[start];
if(testIsPrime(sum)) {
counter++;
}
}else {
sum = ret+numbers[start];
for (int i=start;i<n;i++) {
calc(n,i+1,k-1,sum,value+"-"+i);
}
}
}
public static boolean testIsPrime(int n){
if (n <= 3) {
return n > 1;
}
for(int i=2;i<=Math.sqrt(n);i++){
if(n%i == 0)
return false;
}
return true;
}
}