# include <iostream>
# include <cmath>
# include <algorithm>
# include <stdio.h>
# include <cstdint>
# include <cstring>
# include <string>
# include <cstdlib>
# include <vector>
# include <bitset>
# include <map>
# include <queue>
# include <ctime>
# include <stack>
# include <set>
# include <list>
# include <random>
# include <chrono>
# include <deque>
# include <functional>
# include <iomanip>
# include <sstream>
# include <fstream>
# include <complex>
# include <numeric>
# include <immintrin.h>
# include <cassert>
# include <array>
# include <tuple>
# include <cctype>
# include <unordered_map>
# include <unordered_set>
//#include <bits/stdc++.h>
 
#pragma GCC optimize("Ofast")
//#pragma GCC optimization("unroll-loops, no-stack-protector")
//#pragma GCC target("avx,avx2,fma")
 
#define forn(i, n) for (int i = 0; i < (n); i++)
#define forx(i,x,n) for (int i = x; i < (n); i++)
#define form(i, n) for (int i = n-1; i>=0; i--)
#define all(x) (x).begin(), (x).end()
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define pf push_front
#define mp make_pair
#define ll long long
#define ld long double
#define ull unsigned ll
#define srt(a) sort(a.begin(), a.end());
#define pll pair<ll, ll>
#define pii pair<int,int>
#define pld pair<ld,ld>
#define ar array
#define endl '\n';

using namespace std;
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
template <class T> inline T gcd(T a, T b) { while (b) { a %= b; swap(a, b); } return a; }
template <class T> inline T lcm(T a, T b) { return a * b / gcd(a, b); }
 
const ll MAXN = 2e6 + 7, K = 200043, M = 2500, INF = 1e18 + 7, LOG = 20;
// the good way to get PI number
const ld PI = acos(-1.0);
ll MOD = 1e9 + 7;

template <class T> T sqr(T a) {
    return a * a;
}

ll mul(ll a, ll b) {
    return ((a % MOD) * (b % MOD)) % MOD;
}

ll sum(ll a, ll b) {
    return ((a % MOD) + (b % MOD)) % MOD;
}

ll sub(ll a, ll b) {
    return sum(a, MOD - b);
}

ll bin_pow(ll a, ll n) {
    ll res = 1;
    while (n > 0) {
        if (n & 1)
            res = mul(res, a);
        a = mul(a, a);
        n >>= 1;
    }
    return res;
}

ll inv(ll x) {
    return bin_pow(x, MOD - 2) % MOD;
}

//ll fact[MAXN];
//
//ll C(ll n, ll k) {
//    return mul(mul(fact[n], inv(fact[k])), inv(fact[n - k]));
//}

ll dp[410][410], p[410][410];
ll SIZE = 405;

void solve() {
    int n, c;
    cin >> n >> c;
    vi l(n + 1), r(n + 1);
    for (int i = 1; i <= n; ++i)
        cin >> l[i];
    for (int i = 1; i <= n; ++i)
        cin >> r[i];
    
    for (int i = 1; i < SIZE; ++i)
        p[0][i] = 1;
    
    for (int i = 1; i < SIZE; ++i)
        for (int j = 1; j < SIZE; ++j)
            p[i][j] = mul(p[i - 1][j], j);
    
    for (int i = 0; i < SIZE; ++i)
        for (int j = 1; j < SIZE; ++j)
            p[i][j] = sum(p[i][j], p[i][j - 1]);
    
    for (int i = 0; i <= c; ++i)
        dp[1][i] = sub(p[i][r[1]], p[i][l[1] - 1]);
    
    for (int i = 2; i <= n; ++i)
        for (int j = 0; j <= c; ++j)
            for (int k = 0; k <= j; ++k)
                dp[i][j] = sum(dp[i][j], mul(dp[i - 1][j - k], sub(p[k][r[i]], p[k][l[i] - 1])));
    
    cout << dp[n][c] << endl;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    int t = 1;
//    cin >> t;
    
    while (t --> 0)
        solve();
    return 0;
}



Measured memory_bytes: 6240