#include <bits/stdc++.h>
# define int long long 
#define rep(i, min, max) for(int i = (min); i <= (max); ++i)
#define nrep(i, max, min) for(int i = (max); i >= (min); --i)
#define reads(str) (scanf("%s", str + 1), strlen(str + 1))
#define case() int Ts = read(); rep(T, 1, Ts)
#define putf(flag) puts((flag) ? "Yes" : "No")
#define put(x) printf("%lld ", x)
#define putl(x) printf("%lld ", x)
#define endl() putchar('\n')
using namespace std;

typedef long long ll;
inline int read()
{
    int now=0; bool nev=false; char c=getchar();
    while(c<'0' || c>'9') { if(c=='-') nev=true; c=getchar(); }
    while(c>='0' && c<='9') { now=(now<<1)+(now<<3)+(c&15); c=getchar(); }
    return nev?-now:now;
}

const int N = 1e6 + 10;

int a[N], b[N];
vector<pair<int, int>> vec;
vector<int> ans;

signed main() {
    case() {
        int n = read(), m = read(), k = read(), w = read();
        vec = {}; ans = {};
        rep(i, 1, n) a[i] = read(), vec.push_back({a[i], 1});
        rep(i, 1, m) b[i] = read(), vec.push_back({b[i], 0});
        vec.push_back({w + 1, 0});
        vec.push_back( { 0 , 0 } ) ;
        int lastl = 0, lastr = w + 2, fl = 1, need = 0;
        sort(vec.begin(), vec.end());
        for ( auto t : vec )
        {
        	int x = t.first , op = t.second ;
        	assert( lastl <= lastr ) ;
//        	printf("now:%d %d\n" , x , op) ;
//        	printf("%d %d\n" , lastl , lastr) ;
            if(op == 0) {
                if(need) {
                    if(x <= lastl + k ) { fl = 0; break; }
                    ans.push_back(lastl + 1);
                    need = 0;
                }
                lastl = x; lastr = w + 2;
            } else {
                if(!need) {
                    need = 1;
                    lastr = x - 1;
                    lastl = max( x - k , lastl ) ;
                }
                else
                {
	                if ( x <= lastr + k ) 
					{
						lastl = max(x - k, lastl); 
						continue; 
					}
	                ans.push_back(lastl + 1);
	                lastl = max(x - k, lastl + k);
	                lastr = x - 1;
	            }
            }
		}
//		puts("now:") ;
        if(!fl) { puts("-1"); continue; }
        put(ans.size()), endl();
        for(int i : ans) put(i); endl();
    }
}