#include<bits/stdc++.h>

using namespace std;

#define ll long long
#define all(a) a.begin(),a.end()
#define endl '\n'
 

void solve()
{
   ll n;cin>>n;
   ll ans=n/2;
   if(n%2==0)ans--;
   cout<<ans<<endl;
}

int main()
{
    ios::sync_with_stdio(0); cin.tie(0);
    ll t;cin>>t;
    while(t--)
    {
      solve();
    }    
}