1249A.cpp

/*
*   Author: Rushi Vachhani
*   Platform: Codeforces
*   Problem_ID: 1249A
*   Language: C++
*/

#include<bits/stdc++.h>
using namespace std;

void solve() {
    int n;
    cin >> n;
    int arr[n];
    for(int i=0; i<n; i++) {
        cin >> arr[i];
    }
    sort(arr, arr+n);
    for(int i=0; i<n-1; i++) {
        if(abs(arr[i]-arr[i+1]) == 1) {
            cout<<2<<"\n"; return;
        }
    }
    cout<<1<<"\n"; 
    return;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int t;
    cin >> t;
    while(t--) {
        solve();
    }

    return 0;
}