#include <bits/stdc++.h>

inline int read() {
    bool sym = false; int res = 0; char ch = getchar();
    while (!isdigit(ch)) sym |= (ch == '-'), ch = getchar();
    while (isdigit(ch)) res = (res << 3) + (res << 1) + (ch ^ 48), ch = getchar();
    return sym ? -res : res;
}

void solve() {
    int n = read();
    std::vector<int> a(n + 1);
    std::map<int, int> mp;
    for (int i = 1; i <= n; i++) {
        a[i] = read();
        mp[a[i]]++;
    }
    std::sort(a.begin() + 1, a.end());
    if (a[1] == a[n]) {
        printf("%d\n", n);
        return ;
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        if (i < n && a[i] % 2 == 0 && a[i + 1] == a[i] + 1) {
            ans = std::max(ans, mp[a[i]] + mp[a[i + 1]]);
        }
        ans = std::max(ans, mp[a[i]]);
    }
    printf("%d\n", ans);
}

int main() {
    int T = read();

    while (T--) {
        solve();
    }
    
    return 0;
}