https://zoj.pintia.cn/problem-sets/91827364500/problems/91827370128

include

include

include

include <bits/stdc++.h>

define ALL(x) (x).begin(), (x).end()

define sz(a) int(a.size())

define rep(i,x,n) for(int i=x;i<n;i++)

define repd(i,x,n) for(int i=x;i<=n;i++)

define pii pair<int,int>

define pll pair<long long ,long long>

define gbtb ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)

define MS0(X) memset((X), 0, sizeof((X)))

define MSC0(X) memset((X), '\0', sizeof((X)))

define pb push_back

define mp make_pair

define fi first

define se second

define eps 1e-6

define chu(x) if(DEBUG_Switch) cout<<"["<<#x<<" "<<(x)<<"]"<<endl

define du3(a,b,c) scanf("%d %d %d",&(a),&(b),&(c))

define du2(a,b) scanf("%d %d",&(a),&(b))

define du1(a) scanf("%d",&(a));

using namespace std;
typedef long long ll;
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a / gcd(a, b) * b;}
ll powmod(ll a, ll b, ll MOD) { if (a == 0ll) {return 0ll;} a %= MOD; ll ans = 1; while (b) {if (b & 1) {ans = ans * a % MOD;} a = a * a % MOD; b >>= 1;} return ans;}
ll poww(ll a, ll b) { if (a == 0ll) {return 0ll;} ll ans = 1; while (b) {if (b & 1) {ans = ans * a ;} a = a * a ; b >>= 1;} return ans;}
void Pv(const vector &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%d", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
void Pvl(const vector &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%lld", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
inline long long readll() {long long tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') { fh = -1; } c = getchar();} while (c >= '0' && c <= '9') { tmp = tmp * 10 + c - 48, c = getchar(); } return tmp * fh;}
inline int readint() {int tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') { fh = -1; } c = getchar();} while (c >= '0' && c <= '9') { tmp = tmp * 10 + c - 48, c = getchar(); } return tmp * fh;}
void pvarr_int(int arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%d%c", arr[i], i == n ? '\n' : ' ');}}
void pvarr_LL(ll arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%lld%c", arr[i], i == n ? '\n' : ' ');}}
const int maxn = 3010;
const int inf = 0x3f3f3f3f;
/

define DEBUG_Switch 0

int n, k;
int a[maxn];
int no_prime[2000010];
std::vector v[maxn];
int linked[maxn];
int vised[maxn];
bool dfs(int u)
{
vised[u] = 1;
for (auto x : v[u]) {
if (vised[x]) {
continue;
}
vised[x] = 1;
if (linked[x] == -1 || dfs(linked[x])) {
linked[x] = u;
linked[u] = x;
return 1;
}
}
return 0;
}
int hungarian()
{
int res = 0;
for (int i = 1; i <= n; ++i) {
if (linked[i] == -1) {
repd(j, 1, n) {
vised[j] = 0;
}
if (dfs(i)) {
res++;
}
}
}
return res;
}
int main()
{

if DEBUG_Switch

freopen("D:\\code\\input.txt", "r", stdin);

endif

//freopen("D:\\code\\output.txt","w",stdout);
int t;
for (int i = 2; i < 2000010; ++i) {
    if (no_prime[i] == 1) {
        continue;
    }
    for (int j = i + i; j < 2000010; j += i) {
        no_prime[j] = 1;
    }
}
t = readint();
while (t--) {
    n = readint();
    k = readint();
    repd(i, 1, n) {
        a[i] = readint();
        linked[i] = 0;
        v[i].clear();
    }
    repd(i, 1, n) {
        repd(j, i + 1, n) {
            if (no_prime[a[i] + a[j]] == 0) {
                v[i].push_back(j);
                v[j].push_back(i);
                linked[i] = linked[j] = -1;
            }
        }
    }
    int max_match = hungarian();
    // printf("%d\n", max_match );
    if (max_match >= k) {
        printf("%d\n", 2 * k );
    } else {
        int cnt = 0;
        repd(i, 1, n) {
            if (linked[i] == -1) {
                cnt++;
            }
        }
        int ans = max_match * 2 + min(cnt, k - max_match);
        printf("%d\n", ans );
    }

}

return 0;

}