#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fo(i,a,n) for(ll i=a;i<n;i++)
#define all(v) v.begin(),v.end()
#define pb push_back
#define fi first
#define sc second
#define endl '\n'
#define gcd(x, y) (__gcd(x, y))
#define lcm(x, y) ((x/gcd(x, y))*y)
#define mem(a,b) memset(a, b, sizeof(a))
#define de(x) cerr<<#x<<" :: "<<x<<" "<<endl
void solve()
{
int n;
cin>>n;
if(n%2!=0) {
cout<<n/2<<endl;
}
else {
cout<<((n/2)-1)<<endl;
}
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
int t=1;
cin>>t;
while(t--)
{
solve();
}
return 0;
}