Common Elements

#include<iostream>
using namespace std;

long long int remove_duplicate(long long int a[], long long int n){
    long long int i, j = 0;
    for(i = 0; i < n-1; i++){
        if(a[i] != a[i+1]){
            a[j++] = a[i];
        }
    }
    a[j++] = a[n-1];
    return j;
}

int main(){
    int t; cin >> t;
    while(t--){
        long long int n1, n2, n3; cin >> n1 >> n2 >> n3;
        long long int a[n1], b[n2], c[n3], i;
        //  Taking input
        for(i = 0; i < n1; i++) cin >> a[i];
        for(i = 0; i < n2; i++) cin >> b[i];
        for(i = 0; i < n3; i++) cin >> c[i];

        n1 = remove_duplicate(a, n1);
        n2 = remove_duplicate(b, n2);
        n3 = remove_duplicate(c, n3);

        //  Show array
        /*
        for(i = 0; i < n1; i++) cout << a[i] << ' ';
        cout << endl;
        */
        long long int j = 0, k = 0, flag = 1; i = 0;
        while(i < n1 && j < n2 && k < n3){
            if(a[i] == b[j] && b[j] == c[k]){
                cout << a[i] << ' ';
                i++; j++; k++;
                flag = 0;
            }
            if(a[i] < b[j]) i++;
            else if(b[j] < c[k]) j++;
            else k++;
        }
        if(flag) cout << "-1";
        cout << endl;
    }
}