public static void main(String[] args) throws IOException {
long T, N, K, N_temp, a;
Reader.init(System.in);
T = Reader.nextLong();
while (T-- > 0) {
N = Reader.nextLong();
K = Reader.nextLong();
/*N_temp=N;
while(N_temp-->0)
a=Reader.nextLong();*/
System.out.println(sumbincoef(N - 1, K));
}
}
public static void main(String[] args) throws IOException {
Reader.init(System.in);
int n = Reader.nextInt(), m = Reader.nextInt(), x = Reader.nextInt(), y = Reader.nextInt();
int[] vests = new int[n], solds = new int[m];
for (int i = 0; i < n; i++) vests[i] = Reader.nextInt();
for (int i = 0; i < m; i++) solds[i] = Reader.nextInt();
int p1 = 0, p2 = 0, count = 0;
StringBuilder out = new StringBuilder();
while (p1 < n && p2 < m) {
if (vests[p1] >= solds[p2] - y && vests[p1] <= solds[p2] + x) {
out.append((p1 + 1) + " " + (p2 + 1) + "\n");
p1++;
p2++;
count++;
} else if (vests[p1] < solds[p2] - y) {
p1++;
} else {
p2++;
}
}
System.out.println(count + "\n" + out);
}