#include <cmath>
#include <ctime>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <fstream>
#include <sstream>
#include <vector>
#include <string>
#include <bitset>
#include <queue>
#include <map>
#include <set>

using namespace std;

// Self Template Code BGEIN

#define sz(x) ((int)((x).size()))
#define out(x) printf(#x" %d\n", x)
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define repf(i,a,b) for (int i = (a); i <= (b); ++i)
#define repd(i,a,b) for (int i = (a); i >= (b); --i)
#define repcase int t, Case = 1; for (scanf ("%d", &t); t; --t)
#define repeach(i,x) for (__typeof((x).begin()) i = (x).begin(); i != (x).end(); ++i)

typedef long long int64;
typedef pair<int, int> pii;

int sgn(double x) { return (x > 1e-8) - (x < -1e-8); }
int count_bit(int x) { return x == 0? 0 : count_bit(x >> 1) + (x & 1); }

template<class T> inline void ckmin(T &a, const T b) { if (b < a) a = b; }
template<class T> inline void ckmax(T &a, const T b) { if (b > a) a = b; }

// Self Template Code END

struct point {
    int x, id;
    double v;

    bool operator < (const point& rhs) const {
        return x < rhs.x;
    }
};

const int MAXN = 100000 + 10;

point p[MAXN];
int n, m, k;
int cid[MAXN];

int main() {
    repcase {
        scanf ("%d%d%d", &n, &m, &k);
        rep (i, n) {
            scanf ("%d%lf", &p[i].x, &p[i].v);
            p[i].id = i;
        }
        sort (p, p + n);
        rep (i, n) {
            cid[p[i].id] = i;
        }
        double res = 0;
        rep (i, m) {
            int idx;
            scanf ("%d", &idx);
            idx = cid[idx - 1];
            double ret = 0;
            int l = idx - 1, r = idx + 1;
            rep (j, k) {
                if (l < 0) ret += p[r++].v;
                else if (r >= n) ret += p[l--].v;
                else {
                    int d1 = p[idx].x - p[l].x;
                    int d2 = p[r].x - p[idx].x;
                    if (d1 < d2 || (d1 == d2 && p[l].id < p[r].id)) {
                        ret += p[l--].v;
                    } else {
                        ret += p[r++].v;
                    }
                }
            }
            ret /= k;
            res += ret;
            p[idx].v = ret;
        }
        printf ("%lf\n", res);
    }
    return 0;
}