Codeforces--1335A--Candies and Two Sisters

题目描述：
There are two sisters Alice and Betty. You have n candies. You want to distribute these n candies between two sisters in such a way that:

Alice will get a (a>0) candies;
Betty will get b (b>0) candies;
each sister will get some integer number of candies;
Alice will get a greater amount of candies than Betty (i.e. a>b);
all the candies will be given to one of two sisters (i.e. a+b=n).
Your task is to calculate the number of ways to distribute exactly n candies between sisters in a way described above. Candies are indistinguishable.

Formally, find the number of ways to represent n as the sum of n=a+b, where a and b are positive integers and a>b.

You have to answer t independent test cases.
输入描述:
The first line of the input contains one integer t (1≤t≤104) — the number of test cases. Then t test cases follow.

The only line of a test case contains one integer n (1≤n≤2⋅109) — the number of candies you have.
输出描述:
For each test case, print the answer — the number of ways to distribute exactly n candies between two sisters in a way described in the problem statement. If there is no way to satisfy all the conditions, print 0.
输入：
6
7
1
2
3
2000000000
763243547
输出：
3
0
0
1
999999999
381621773
题意：
一个数分解成a+b，几种分解法，a!=b
题解：
分奇偶讨论一下
代码：

#include
#include
#include
#include
using namespace std;

int main(){
    int t,n;
    scanf("%d",&t);
    while(t--){
        scanf("%d",&n);
        int ans;
        if(n % 2 == 0){
            ans = n / 2 - 1;
        }
        else ans = n / 2;
        printf("%d\n",ans);
    }
    return 0;
}