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#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

using u128 = unsigned __int128;
using i128 = __int128;

namespace rgs = std::ranges;
std::vector<int> minp, primes;

void sieve(int n) {
    minp.assign(n + 1, 0);
    primes.clear();
    
    for (int i = 2; i <= n; i++) {
        if (minp[i] == 0) {
            minp[i] = i;
            primes.push_back(i);
        }
        
        for (auto p : primes) {
            if (i * p > n) {
                break;
            }
            minp[i * p] = p;
            if (p == minp[i]) {
                break;
            }
        }
    }
}

constexpr int inf = 1E9;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n, q;
    std::cin >> n >> q;
    
    sieve(n);
    
    std::set<int> set;
    std::vector<int> a(q), sgn(q);
    for (int i = 0; i < q; i++) {
        std::cin >> a[i];
        a[i]--;
        if (set.contains(a[i])) {
            sgn[i] = -1;
            set.erase(a[i]);
        } else {
            sgn[i] = 1;
            set.insert(a[i]);
        }
    }
    
    set.clear();
    std::vector<int> ans(q), cnt(n);
    
    std::vector<int> freq(n + 1), num(n);
    
    std::vector<int> cand;
    
    for (int i = 0; i < q; ) {
        const int m = set.size();
        const int step = std::min(q - i, std::max(1, m / 4));
        
        std::vector S(set.begin(), set.end());
        
        const int groups = std::max(1, m / 6);
        cand.clear();
        for (int i = 0, l = 0; i < m; i++) {
            if (i % 6 == 0 && i + 5 < m) {
                l = i;
            }
            for (int j = l; j < i; j++) {
                int d = S[i] - S[j];
                while (d > 1) {
                    const int p = minp[d];
                    if (++cnt[p] == 1) {
                        cand.push_back(p);
                    }
                    d /= p;
                }
            }
        }
        
        for (auto p : cand) {
            if (cnt[p] >= groups) {
                int cur = 0;
                freq[0] = inf;
                auto add = [&](int x, int y) {
                    freq[num[x]]--;
                    num[x] += y;
                    freq[num[x]]++;
                    cur = std::max(cur, num[x]);
                    if (!freq[cur]) {
                        cur--;
                    }
                };
                
                for (auto x : S) {
                    add(x % p, 1);
                }
                
                for (int j = i; j < i + step; j++) {
                    add(a[j] % p, sgn[j]);
                    ans[j] = std::max(ans[j], cur);
                }
                
                for (auto x : S) {
                    const int v = x % p;
                    freq[num[v]] = 0;
                    num[v] = 0;
                }
                
                for (int j = i; j < i + step; j++) {
                    const int v = a[j] % p;
                    freq[num[v]] = 0;
                    num[v] = 0;
                }
            }
            cnt[p] = 0;
        }
        
        for (int j = i; j < i + step; j++) {
            if (sgn[j] == 1) {
                set.insert(a[j]);
            } else {
                set.erase(a[j]);
            }
            if (set.size() == 1) {
                ans[j] = 1;
            } else if (set.size() == 2) {
                int x = *set.begin();
                int y = *std::next(set.begin());
                ans[j] = x + 1 == y ? 1 : 2;
            } else if (set.size() == 3) {
                int x = *set.begin();
                int y = *std::next(set.begin());
                int z = *set.rbegin();
                ans[j] = std::gcd(y - x, z - y) > 1 ? 3 : 2;
            }
            ans[j] = std::max(ans[j], int(set.size() + 1) / 2);
        }
        
        i += step;
    }
    for (int i = 0; i < q; i++) {
        std::cout << ans[i] << "\n";
    }
    
    return 0;
}