#include<bits/stdc++.h>
using namespace std;
const int mx=1e7+123;
vector<int>divisors[mx];
#define endl '\n'
#define ll long long int
#define optimize() ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
int main()
{
    ll n,t;
    cin>>t;
    while(t--){
      cin>>n;
      if(n%2==0) cout<<(n/2)-1<<endl;
      else cout<<n/2<<endl;
    }
}