NCS

#define task "NCS"
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>

using namespace std;

using ll = long long;
using ld = long double;

constexpr int N = 1e4 + 5;
constexpr int mod = 123456789;
int m, n;
int a[N], b[N], dp[N], f[N];
vector<int> s;
vector<int> pos[N * 2];

void Read()
{
    cin >> m >> n;

    for (int i = 1; i <= m; ++i)
    {
        cin >> a[i];
        s.emplace_back(a[i]);
    }

    for (int i = 1; i <= n; ++i)
    {
        cin >> b[i];
        s.emplace_back(b[i]);
    }
}

#define Find(x, v) (lower_bound(x.begin(), x.end(), v) - x.begin() + 1)
void Compress()
{
    sort(s.begin(), s.end());
    s.resize(unique(s.begin(), s.end()) - s.begin());

    for (int i = 1; i <= m; ++i)
        a[i] = Find(s, a[i]);
    for (int i = 1; i <= n; ++i)
        b[i] = Find(s, b[i]);
}

void Solve()
{
    for (int i = 1; i <= n; ++i)
        pos[b[i]].emplace_back(i);

    dp[0] = 1;

    for (int i = 1; i <= m; ++i)
    {
        for (int j = 0; j <= n; ++j)
        {
            if (a[i] == b[j])
                f[j] = dp[j - 1];
            else
                f[j] = dp[j];

            if (j)
                (dp[j] += dp[j - 1]) %= mod;
        }

        for (int j = (int)pos[a[i]].size() - 1; j; --j)
            (f[pos[a[i]][j]] -= f[pos[a[i]][j - 1]]) %= mod;

        swap(f, dp);
    }

    int ans(0);

    for (int i = 1; i <= n; ++i)
        (ans += dp[i]) %= mod;

    cout << (ans + mod) % mod;
}

int32_t main()
{
    ios_base::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();
    Compress();
    Solve();
}