#include<bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds;

#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ll long long
#define all(v) (v).begin(), (v).end()
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
#define F first 
#define S second

const ll M = 1e18 + 7;
const int N = 1e5 + 7;
const int MOD = 1e9 + 7;



void Hrid_solve(){
    ll n;
    cin >> n;

    if(n&1) cout << n/2 << endl;
    else cout << (n/2)-1 << endl;
    
}


/* ************** What defines us is how well we rise after we Fall !! ************** */

int32_t main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
 
    int tc = 1;
    cin >> tc;
    for(int kase = 1; kase <= tc; kase++){
        // cout << "Case " << kase << ": ";
        Hrid_solve();
    }

    return 0;
}