C :

#include<stdio.h>
#include<string.h>
#include<math.h>
int judge(int a)
{
	if(a==1||a==0)
	return 0;
	for(int i=2;i<=sqrt(a);i++)
	if(a%i==0)
	return 0;
	return 1;
}
main()
{
	int num[26],i,max,min,n;
	char ch[128];
	scanf("%d",&n);
	while(n--)
	{
		memset(num,0,sizeof(num));
		scanf("%s",&ch);
		for(i=0;i<strlen(ch);i++)
		num[ch[i]-97]++;
		for(i=0,max=0,min=128;i<26;i++)
		{
			if(num[i]>max)
			max=num[i];
			if(num[i]<min&&num[i]!=0)
			min=num[i];
		}
		if(strlen(ch)==max)
		min=0;
		if(judge(max-min))
		{
			puts("Lucky Word");
			printf("%d\n",max-min);
		}
		else
		{
			puts("No Answer\n0");
		}
	}
}

C++ :

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
int isPrime(int a)
{
	int i;
	if(a == 0 ||a ==1)return 0;
	if(a == 2)return 1;
	for(i = 2;i <= sqrt( a );i++)
	{
		if(a % i == 0)return 0;
	}
	return 1;
}
int letter[30];
char word[110];
int main()
{
	int n ,i , maxn , minn ,temp;
	//freopen("1.in", "r", stdin); 
	//freopen("1.out", "w", stdout);
	scanf("%d",&n);
	while(n--)
	{
		maxn = -1;
		minn = 101;
		memset(letter , 0 , sizeof(letter));
		scanf("%s",word);
		for(i=0 ; i < strlen(word);i++)
		{
			letter[word[i]-'a']++;
		}
		for(i = 0 ; i <30 ; i++ )
		{
			if(letter[i] >= maxn)
			maxn = letter[i];
			if(letter[i] <= minn && letter[i]!=0)
			minn = letter[i];
		}
		temp = isPrime(maxn - minn);
		if(temp == 1)
		{
			printf("Lucky Word\n");
			printf("%d\n",maxn - minn);
		}
		else
		{
			printf("No Answer\n");
			printf("0\n");
		}
	}
}