#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n, m;
vector<int> a, b;

bool ok(int mid){
    for (int i=1; i * i <= mid; i++){
        int di = (mid - 1) / i + 1;
        map<int, int> ma;
        int amax = -1e9, bmin = 1e9;
        if (i <= n && di <= m){
            for (int j=0; j<i; j++){
                ma[a[j]]++;
            }
            amax = max(amax, ma.begin()->first);
            for (int j=i; j<n; j++){
                ma[a[j]]++;
                ma[a[j-i]]--;
                if (!ma[a[j-i]]) ma.erase(a[j-i]);
                amax = max(amax, ma.begin()->first);
            }
            ma.clear();
            for (int j=0; j<di; j++){
                ma[b[j]]++;
            }
            bmin = min(bmin, ma.rbegin()->first);
            for (int j=di; j<m; j++){
                ma[b[j]]++;
                ma[b[j-i]]--;
                if (!ma[b[j-i]]) ma.erase(b[j-i]);
                bmin = min(bmin, ma.rbegin()->first);
            }
        }
        if (amax >= bmin) return true;
        amax = -1e9;
        bmin = 1e9;
        ma.clear();
        if (di <= n && i <= m){
            for (int j=0; j<di; j++){
                ma[a[j]]++;
            }
            amax = max(amax, ma.begin()->first);
            for (int j=di; j<n; j++){
                ma[a[j]]++;
                ma[a[j-i]]--;
                if (!ma[a[j-i]]) ma.erase(a[j-i]);
                amax = max(amax, ma.begin()->first);
            }
            ma.clear();
            for (int j=0; j<i; j++){
                ma[b[j]]++;
            }
            bmin = min(bmin, ma.rbegin()->first);
            for (int j=i; j<m; j++){
                ma[b[j]]++;
                ma[b[j-i]]--;
                if (!ma[b[j-i]]) ma.erase(b[j-i]);
                bmin = min(bmin, ma.rbegin()->first);
            }
        }
        if (amax >= bmin) return true;
    }
    return false;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> m;
    a.resize(n);
    b.resize(m);
    for (int &x : a){
        cin >> x;
    }
    for (int &x : b){
        cin >> x;
    }
    int l = 0, r = n * m + 1;
    while (l + 1 < r){
        int mid = (l + r) / 2;
        if (ok(mid)){
            l = mid;
        }
        else{
            r = mid;
        }
    }
    cout << l;
}