import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
 
        // Read the number of test cases
        int t = sc.nextInt();
        for (int i = 0; i < t; i++) {
            // Read the number of students who cheated
            int n = sc.nextInt();
            // Initialize the boolean array to track which student passed the solution
            boolean[] passed = new boolean[n + 1];
 
            // Read the IDs of the students who cheated
            for (int j = 1; j <= n; j++) {
                int id = sc.nextInt();
                passed[id] = true;
            }
 
            // Find the student who leaked the solution
            int cheaterId = 0;
            for (int j = 1; j <= n; j++) {
                if (!passed[j]) {
                    cheaterId = j;
                    break;
                }
            }
 
            // Output the ID of the cheater who leaked the solution
            System.out.println(cheaterId);
        }
    }
}