提交之后显示编译失败

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;

bool fun(int x)//判断质数
{
	bool flag = true;
	for (int i = 2; i <= sqrt(x); i++)
	{
		if (x % i == 0)
		{
			flag = !flag;
			break;
		}
	}
	return flag;
}
int main()
{
	string a;
	cin >> a;
	int maxn = 0, minn = 0;
	int b[100] = { 0 }, zz1 = 0;//出现过的字母出现的次数
	char c[26], zz2 = 0;//储存已出现过的字母
	for (int i = 0; i < a.length(); i++)
	{
		int flag = 0;
		for (int k = 0; k < zz2; k++)//判断该字母是否已经出现过
		{
			if (c[k] == a[i])
			{
				flag = 1;
				break;
			}
		}
		if (flag == 0)
		{
			int num = 1;
			for (int j = i + 1; j < a.length(); j++)//统计该字母出现了几次
			{
				if (a[j] == a[i])
					num++;
			}
			b[zz1++] = num;
		}
	}
	sort(b, b + zz1);//对每个字母出现的次数排序（这时就不考虑是哪个字母出现的次数了）
	maxn = b[zz1 - 1];
	minn = b[0];
	if (fun(maxn - minn))
	{
		cout << "Lucky Word" << endl;
	}
	else
	{
		cout << "No Answer" << endl;
	}
	cout << maxn - minn << endl;
	return 0;
}