谁帮我看下哥德巴赫猜想的程序哪里有错误啊

#include<iostream>
#include<math.h>
using namespace std;
bool k;
int main()
{
void gotbaha(int n);
int n;
cout << "输入一个大于等于6的偶数：" << endl;
cin >> n;
gotbaha(n);
return 0;
}
void gotbaha(int n)
{
int a, b;
int prime(int n);
for (int i = 3; i <=(n-3);i++)
if (i % 2 != 0) {
a = prime(i); b = prime(n - i);
if (a > 0 && b > 0)
cout << n << "=" << a << "+" << b << endl;
}
}
int prime(int m)
{
for (int i =2; i <= sqrt(m); i++)
{
if (m%i == 0) k = false;
else k = true;
}
if (k)
return m;
}