Decipher password (comprehensive)

describe

There's a man named “ Pig head Gang ” The country , Using a simple grammar encryption , The language they use is capital letters , There are no other characters ; Now we know that their encryption method is ： Only one capital letter is used to XOR with the original text to generate ciphertext . Please help untie .

Input
There are several groups , Each group of inputs has 2 That's ok , The first line of integers N Express N A ciphertext , The next line is N The integers represent N A ciphertext .

Output
Output the original text with only capital letters .

sample input 1

30
17 6 9 8 3 0 1 6 7 4 5 10 11 8 9 14 15 12 13 18 19 16 17 22 23 20 21 26 27 24

sample output 1

SDKJABCDEFGHIJKLMNOPQRSTUVWXYZ

#include<stdio.h>

int main(){
    
	int n,i,j,c;
	int a[100];
	int flag;
	while(scanf("%d",&n)!=EOF){
    
		for(i=0;i<n;i++){
    
			scanf("%d",&a[i]);
		}
		for(j='A';j<='Z';j++){
    
			flag = 1;
			for(i=0;i<n;i++){
    
				if((a[i]^j)<'A' || (a[i]^j)>'Z'){
    
					flag = 0;
					break;
				}
			}
			if(flag){
    
				c = j;
				break;
			}
		}
		for(i=0;i<n;i++){
    
			printf("%c",(char)(a[i]^c));
		}
		printf("\n");
	}
}