// compile: g++ -o data data.cpp -O3 -std=gnu++20 -Wall -Wextra -Wshadow -D_GLIBCXX_ASSERTIONS -ggdb3 -fmax-errors=2 -DLOCAL
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) {_variables(#x);_print(x);}
#else
#define debug(x...)
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define rep(i,a,b) for(int i=(a);i<(int)(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define INTMAX (int)(9223372036854775807)
#define INTINF (int)(1152921504606846976)
#define int long long
#define MAXN 200010

map<int, int> mp;

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int n, m; cin >> n >> m;
    vector<int> s(n-1), x(m), a(n);
    rep(i, 0, n-1) cin >> s[i];
    rep(i, 0, m) cin >> x[i];
    rep(i, 1, n) a[i] = s[i-1] - a[i-1];
    rep(i, 0, n) {
        int d = i&1 ? -1 : 1;
        rep(j, 0, m) ++mp[(x[j] - a[i]) * d];
    }
    int ans = 0;
    for (auto [key, value]: mp) ans = max(ans, value);
    cout << ans << endl;

    return 0;
}