THẦN SỐ HỌC CHUYÊN SÂU

#define task "NROLOGY"
#include <bits/stdc++.h>

using namespace std;
using ll = long long;

constexpr int N = 5e2 + 5;
constexpr ll mod = 1e9 + 7;
string b, s;

ll dp[N][N][2][3], cnt[N][N][2][3];
ll Pow[N];

ll d[N][N], c[N][N];

int n, m;

void Read()
{
    cin >> s >> b;

    reverse(b.begin(), b.end());

    while (b.size() < s.size())
        b.push_back('0');
    reverse(b.begin(), b.end());

    n = b.size();
    m = s.size();
    b = " " + b + " ";
    s = " " + s + " ";
}

ll toll(const string s)
{
    ll ans(0);

    for (auto i : s)
        ans = ans * 10 + i - '0';

    return ans;
}

#define bit(i, x) (((x) >> (i)) & 1)

ll f(int l, int r, bool okl, int okr)
{

    ll &ans = dp[l][r][okl][okr], &res = cnt[l][r][okl][okr];

    if (ans != -1)
        return ans;

    int pos = n - (l + (n + 1 - r));

    if (pos == 0)
    {
        res = (okl || okr != 2);
        return ans = 0;
    }

    ans = 0;
    res = 0;

    if (okl || s[pos] <= b[l + 1])
    {
        (ans += f(l + 1, r, okl || s[pos] < b[l + 1], okr)) %= mod;
        (ans += (s[pos] - '0') * Pow[n - (l + 1)] % mod * cnt[l + 1][r][okl || s[pos] < b[l + 1]][okr] % mod) %= mod;
        (res += cnt[l + 1][r][okl || s[pos] < b[l + 1]][okr]) %= mod;
    }

    {
        int t;

        if (s[pos] > b[r - 1])
            t = 2;
        else if (s[pos] < b[r - 1])
            t = 1;
        else
            t = okr;

        (ans += f(l, r - 1, okl, t)) %= mod;
        (ans += (s[pos] - '0') * Pow[n - (r - 1)] % mod * cnt[l][r - 1][okl][t] % mod) %= mod;
        (res += cnt[l][r - 1][okl][t]) %= mod;
    }

    return ans;
}

ll g(int l, int r)
{
    ll &ans = d[l][r],
       &res = c[l][r];

    if (ans != -1)
        return ans;

    ans = 0;
    res = 0;

    int pos = m - (l + (m + 1 - r));

    if (l + 1 == r)
    {
        res = 1;
        return 0;
    }

    {
        (ans += g(l + 1, r)) %= mod;
        (ans += (s[pos] - '0') * Pow[m - (l + 1)] % mod * c[l + 1][r] % mod) %= mod;
        (res += c[l + 1][r]) %= mod;
    };
    {
        (ans += g(l, r - 1)) %= mod;
        (ans += (s[pos] - '0') * Pow[m - (r - 1)] % mod * c[l + 1][r] % mod) %= mod;
        (res += c[l][r - 1]) %= mod;
    }

    return ans;
}

void Solve()
{
    Pow[0] = 1;

    for (int i = 1; i <= n; ++i)
        Pow[i] = Pow[i - 1] * 10 % mod;

    if (s.size() < b.size())
    {
        memset(d, -1, sizeof d);
        cout << g(0, m + 1) * 500000004 % mod;
    }
    else
    {
        memset(dp, -1, sizeof dp);
        cout << f(0, n + 1, 0, 0) * 500000004 % mod;
    }
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen(task ".INP", "r"))
    {
        freopen(task ".INP", "r", stdin);
        freopen(task ".OUT", "w", stdout);
    }
    Read();
    Solve();
}