#include <bits/stdc++.h>

const double PI = 3.14159265358979323846;
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
#define rep(i, n) for (int i = 0; i < (n); ++i)
//#define rep(i, n) for (ll i = 0; i < (n); ++i)
//typedef pair<ll, ll> P;
typedef pair<double, ll> P;
const ll INF = 10e17;
#define cmin(x, y) x = min(x, y)
#define cmax(x, y) x = max(x, y)
#define ret() return 0;

std::istream &operator>>(std::istream &in, set<int> &o) {
    ll a;
    in >> a;
    o.insert(a);
    return in;
}

std::istream &operator>>(std::istream &in, queue<int> &o) {
    ll a;
    in >> a;
    o.push(a);
    return in;
}

bool contain(set<int> &s, int a) { return s.find(a) != s.end(); }

//ifstream myfile("C:\\Users\\riku\\Downloads\\0_00.txt");
//ofstream outfile("log.txt");
//outfile << setw(6) << setfill('0') << prefecture << setw(6) << setfill('0') << rank << endl;
// std::cout << std::bitset<8>(9);

//const ll mod = 1e10;
typedef priority_queue<string, vector<string>, greater<string> > PQ_ASK;

const int mod = 1000000007;

struct mint {
    ll x; // typedef long long ll;
    mint(ll x = 0) : x((x % mod + mod) % mod) {}

    mint &operator+=(const mint a) {
        if ((x += a.x) >= mod) x -= mod;
        return *this;
    }

    mint &operator-=(const mint a) {
        if ((x += mod - a.x) >= mod) x -= mod;
        return *this;
    }

    mint &operator*=(const mint a) {
        (x *= a.x) %= mod;
        return *this;
    }

    mint operator+(const mint a) const {
        mint res(*this);
        return res += a;
    }

    mint operator-(const mint a) const {
        mint res(*this);
        return res -= a;
    }

    mint operator*(const mint a) const {
        mint res(*this);
        return res *= a;
    }

    mint pow(ll t) const {
        if (!t) return 1;
        mint a = pow(t >> 1);
        a *= a;
        if (t & 1) a *= *this;
        return a;
    }

    // for prime mod
    mint inv() const {
        return pow(mod - 2);
    }

    mint &operator/=(const mint a) {
        return (*this) *= a.inv();
    }

    mint operator/(const mint a) const {
        mint res(*this);
        return res /= a;
    }

    friend std::istream &operator>>(std::istream &in, mint &o) {
        ll a;
        in >> a;
        o = a;
        return in;
    }

    friend std::ostream &operator<<(std::ostream &out, const mint &o) {
        out << o.x;
        return out;
    }

};

class CumulativeSum {
    vector<mint> numbers;
    vector<mint> sums;

public:
    CumulativeSum(int n = 0) {
        numbers.resize(n);
        sums.resize(n);
    }

    void set(int i, mint value) {
        numbers[i] = value;
    }

    mint getSum(int i) {
        if (i == -1) return 0;
        if (i == sums.size()) return sums.back();
        return sums[i];
    }

    mint getSectionSum(int start, int end) {
        return getSum(end) - getSum(start - 1);
    }

    void build() {
        for (int i = 0; i < numbers.size(); i++) {
            sums[i] = getSum(i - 1) + numbers[i];
        }
    }

};

mint siguma(vector<CumulativeSum> &css, int k, int a, int b) {
    return css[k].getSectionSum(a, b);
}

int main() {
    int n, c;
    cin >> n >> c;


    vector<ll> v(n), u(n);
    rep(i, n) cin >> v[i];
    rep(i, n) cin >> u[i];

    vector<CumulativeSum> css(c + 1);
    rep(k, c + 1) {
        css[k] = CumulativeSum(500);
        rep(j, 500) {
            css[k].set(j, mint(j).pow(k));
        }
        css[k].build();

    }

    vector<vector<mint>> dp(n + 1, vector<mint>(c + 1, 0));
    dp[0][0] = 1;

    rep(i, n) {
        rep(j, c + 1) {
            rep(k, c + 1) {
                if (j + k > c) continue;
                dp[i + 1][j + k] += (dp[i][j] * siguma(css, k, v[i], u[i]));
            }
        }
    }

    cout << dp[n][c] << endl;
}


Measured memory_bytes: 4736