#include <bits/stdc++.h>
using namespace std;
#define ll long long 
 
int main(){
	int t;
	cin>>t;
 
	while(t--){
		int n;
		cin>>n;
 
		if(n<=2){
			cout<<0<<endl;
		}else if(n==3){
			cout<<1<<endl;
		}else{
			n-=2;
 
			cout<<n/2<<endl;
		}
	}
}
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