#include <cstdio>

int main(int argc, char** argv) {
	setbuf(stdout, NULL);
	int TC;
	int test_case;
    
	scanf("%d", &TC);
	for(test_case = 1; test_case <= TC; test_case++) {
	    int n, x=0;
	    scanf("%d",&n);
	    
	    for(int i=0;i<n;i++){
	        int t;
	        scanf("%d",&t);
	        x=x^t;
	    }
	    
        printf("Case #%d\n", test_case);
        printf("%d\n", x);
	}
	return 0;
}

#include <stdio.h>

int main(int argc, char** argv) {
	
	setbuf(stdout, NULL);

	int TC;
	int test_case;

	scanf("%d", &TC);
	for (test_case = 1; test_case <= TC; test_case++) {
		int n;
		int temp;
		int ans = 0;
		scanf("%d", &n);
		for (int i = 0; i < n; i++){
			scanf("%d", &temp);
			ans ^= temp;
		}
	printf("Case #%d\n", test_case);
		printf("%d\n", ans);

	}

	return 0;
}