初学求助：这个思路为什么不对？

#include<cstdio>
#include<cmath>
using namespace std;
int a[21],s=0,m=0,n,k,ans=0;
bool check(int x){
    int i;
    bool e=0;
    for(i=2;i<x/2;i++){
        if(x%2==0){
            e=1;
            break;}}
    if(e)return 0;
    if(!e)return 1;
}
void dfs(int q){
    for(;q<=n;q++){
        s+=a[q];
        m++;
        if(m!=k)dfs(q+1);
        if(check(s))ans++;
        s=s-a[q];
        m--;}
}
int main(){
    freopen("choose.in","r",stdin);
    freopen("choose.out","w",stdout);
    scanf("%d%d",&n,&k);
    int i;
    for(i=1;i<=n;i++){
        scanf("%d",&a[i]);}
    dfs(1);
    printf("%d",ans);
    return 0;
}