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

void solve(int t) {
    int n;
    cin >> n;

    int x; 
    map<int, int> cnt;
    int mx = 0;
    
    for (int i = 0; i<n; i++){
        cin >> x;
        cnt[x-i]++;
        mx = max(mx,cnt[x]);
    }
    cout << n - mx << '\n';
}

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