#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <math.h>
#include <assert.h>
#include <queue>
#include <map>
#include <set>
#include <string>
#include <algorithm>
#include <iostream>
#include <functional>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <bitset>
using namespace std;
typedef pair<int, int> Pi;
typedef long long ll;
#define pii Pi
#define pll PL
#define Fi first
#define Se second
#define pb(x) push_back(x)
#define sz(x) ((int)(x).size())
#define rep(i, n) for(int i=0;i<n;i++)
#define all(x) (x).begin(), (x).end()
typedef tuple<int, int, int> t3;
typedef pair<ll, ll> PL;
int n, k;
int A[110], B[110];
const int MOD = 1e9 + 7;
void subtask_1(){
int p[8] = {}, ans = 0;
rep(i, n)p[i] = i;
do{
int aa = 1e9, bb = 0;
rep(i, n){
if(i < k)aa = min(aa, A[i] + B[p[i]]);
else bb = max(bb, A[i] + B[p[i]]);
}
if(aa >= bb)ans++;
}while(next_permutation(p, p+n));
printf("%d\n", ans);
}
void subtask_2(){
ll ans = 0;
for(int i=0;i<n;i++){
int aa = A[0] + B[i];
int v[110] = {};
for(int j=1;j<n;j++){
int c = 0;
for(int k=0;k<n;k++)if(i != k && B[k] + A[j] <= aa)++c;
for(int k=1;k<=c;k++)v[k]++;
}
ll now = 1;
for(int j=n-1;j;j--){
now = now * v[j] % MOD;
for(int k=j;k;k--)v[k]--;
}
ans = (ans + now) % MOD;
}
printf("%lld\n", ans);
}
void subtask_3_get(int k, int *A, vector <int> &v, vector <Pi> &res, int inv){
rep(a, k){
rep(b, k){
int t = A[a] + v[b];
vector <int> cv(k+1, 0);
rep(c, k){
int cnt = 0;
rep(d, k)if(inv * (A[c] + v[d]) >= inv * t)cnt++;
cv[cnt]++;
}
ll g = 1;
for(int c=k, r=0;c;c--){
g = (cv[c] + r) * g % MOD;
r += cv[c] - 1;
}
res.pb(Pi(t, (int)g));
}
}
sort(all(res));
}
void subtask_3(){
if(k == n){
ll ans = 1;
rep(i, n)ans = ans * (i+1) % MOD;
printf("%lld\n", ans);
return;
}
ll ans = 0;
for(int i=0;i<1<<n;i++){
if(__builtin_popcount(i) != k)continue;
vector <int> v, w;
rep(j, n){
if(1<<j & i)v.pb(B[j]);
else w.pb(B[j]);
}
vector <Pi> av, aw;
subtask_3_get(k, A, v, av, 1); //min
subtask_3_get(n-k, A+k, w, aw, -1); //max
for(int j=sz(aw)-1;j;j--)aw[j].Se = (aw[j].Se - aw[j-1].Se + MOD) % MOD;
for(int j=0;j<sz(aw);j++){
int ww = aw[j].Fi;
auto it = lower_bound(all(av), Pi(ww, -1));
if(it != av.end())ans = (ans + (ll)aw[j].Se * (lower_bound(all(av), Pi(ww, -1))->Se)) % MOD;
}
}
printf("%lld\n", ans);
}
void solve(){
scanf("%d%d", &n, &k);
rep(i, n)scanf("%d", A+i);
rep(i, n)scanf("%d", B+i);
sort(A, A+n); reverse(A, A+n);
sort(B, B+n); reverse(B, B+n);
int debug = 0;
if(n <= 8){
subtask_1();
if(!debug)return;
}
if(k == 1){
subtask_2();
if(!debug)return;
}
if(n <= 15){
subtask_3();
}
}
int main(){
int Tc = 1; //scanf("%d", &Tc);
for(int tc=1;tc<=Tc;tc++){
//printf("Case #%d: ", tc);
solve();
}
return 0;
}
