//qoj6339
#include <bits/stdc++.h>
using namespace std;

const int N = 15010;
int n, m, a[N], b[N], c[N], pr[N], cnt[N], mx;
int f[N], fr[N];
pair<int, int> aa[N];

int main(){
    scanf("%d", &n);
    for(int i = 1; i <= n; ++ i){
        scanf("%d", &a[i]);
        mx = max(mx, a[i]);
        aa[i] = make_pair(a[i], i);
        for(int j = 1; j <= a[i]; ++ j){
            ++ c[j];
        }
    }
    int tp = 0;
    for(int i = 1; i <= mx; ++ i){
        for(int j = 1; j <= c[i]; ++ j){
            pr[++tp] = i;
            cnt[tp] = j;
        }
    }
    scanf("%d", &m);
    for(int i = 1; i <= m; ++ i){
        scanf("%d", &b[i]);
    }
    sort(aa + 1, aa + n + 1);
    reverse(aa + 1, aa + n + 1);
    sort(b + 1, b + m + 1);
    reverse(b + 1, b + m + 1);
    memset(f, 0x3f, sizeof(f));
    f[0] = 0;
    cnt[0] = 1e9;
    for(int i = 1; i <= tp; ++ i){
        for(int j = 1; j <= m; ++ j){
            if(i >= b[j]){
                if(pr[i] == pr[i-b[j]+1]){
                    f[i] = min(f[i], f[i-b[j]] + 1);
                    if(f[i] == f[i-b[j]] + 1){
                        fr[i] = i - b[j];
                    }
                } else if(pr[i] == pr[i-b[j]+1] + 1 && cnt[i] < cnt[i-b[j]+1]){
                    f[i] = min(f[i], f[i-b[j]] + 1);
                    if(f[i] == f[i-b[j]] + 1){
                        fr[i] = i - b[j];
                    }
                }
            }
        }
    }
    if(f[tp] > 100000){
        puts("-1");
        return 0;
    }
    printf("%d\n", f[tp]);
    int x = tp;
    for(int i = 1; i <= f[tp]; ++ i){
        printf("%d ", x - fr[x]);
        for(int j = fr[x] + 1; j <= x; ++ j){
            printf("%d ", aa[cnt[j]].second);
        }
        puts("");
        x = fr[x];
    }
    return 0;
}