#define _CRT_SECURE_NO_WARNINGS
#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
#include <bits/stdc++.h>
using namespace std;
const int N = 10050;
int a[N];
int main()
{
    int T, n;
    cin >> T;
    while (T--)
    {
        cin >> n;
        for (int i = 0; i < n; i++)
            scanf("%d", a + i);
        int cur = 1, ans = 1;
        for (int i = 1; i < n; i++)
            if (a[i] == a[i - 1] + 1)
                cur++;
            else
                ans = max(ans, cur), cur = 1;
        cout << max(ans, cur) << endl;
    }
    return 0;
}