#include <iostream>

#define x first
#define y second

using namespace std;

typedef long long LL;
typedef pair<int, int> PII;

const int N = 1e5 + 100, M = N << 1;

PII p[M];

PII operator - (PII a, PII b)
{
    return { a.x - b.x, a.y - b.y };
}

LL operator * (PII a, PII b)
{
    return (LL)a.x * b.y - (LL)a.y * b.x;
}

LL area(PII a, PII b, PII c)
{
    return (b - a) * (c - a);
}

void March_April()
{
    int n, k;
    scanf("%d%d", &n, &k);

    for(int i = 1; i <= n; i ++)
        scanf("%d%d", &p[i].x, &p[i].y), p[i + n] = p[i];

    LL ans = 0, res = 0;

    for(int i = 1; i + 1 <= 1 + k; i ++)
        res += p[i] * p[i + 1];

    for(int i = 1, j = 1; i <= n; i ++)
    {
        while(j <= i + k)    j ++;
        while(j < i + n && abs(area(p[i], p[i + k], p[j])) <= abs(area(p[i], p[i + k], p[j + 1])))
            j ++;

        ans = max(ans, res + p[i + k] * p[j] + p[j] * p[i]);

        // clog << i << " " << j << " " << res + p[j + k] * p[i] + p[i] * p[j] << '\n';

        res -= p[i] * p[i + 1], res += p[i + k] * p[i + k + 1];
    }

    if(ans % 2) printf("%lld.5\n", ans / 2);
    else    printf("%lld\n", ans / 2);
}

int main()
{
    int T;
    scanf("%d", &T);

    while(T --)
        March_April();

    return 0;
}