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

const int N = 3e5 + 9;
const int inf = 3e10 + 9;

int a[N], b[N];
int dp[1003][103];

string s[N];

vector<int> v[7];

std::map<string, int> mp;

int32_t main() {

    int tc = 1;
    cin >> tc;
    while(tc--) {
        int n; cin >> n;
        cout << (n / 2) - (n % 2 == 0) << endl;
    }

    return 0;
}