#include <bits/stdc++.h>
typedef long long int ll;
#define endl            '\n'
#define pb             push_back
#define l first
#define r second
#define mp              make_pair
#define pll             pair<ll,ll> 
#define fill(x, y)     memset(x, y, sizeof(x))
#define all(x)         (x).begin(), (x).end()
#define debug(x)       { cerr << #x << " = " << x << endl; }
#define IO	       { ios_base::sync_with_stdio(false); cin.tie(0); }
#define read(x)	       freopen(x, "r", stdin)
#define write(x)       freopen(x, "w", stdout)


using namespace std;

typedef vector<int> vi;
typedef pair<int, int> ii;

const int N = 2000;
int dp[N][2];
int al[N][2];
vector<ii> canvas;
vector<int> pegs;
map<int, bool> atPos;

const int inf = 1e8;

int n, p;
int solve(int pos, int peg) {
    if (pos == n) return 0;
    if (dp[pos][peg] != -1) return dp[pos][peg];

    int already = 0;
    for (int i=0; i<pegs.size(); i++) 
        if (pegs[i] >= canvas[pos].first and pegs[i] <= canvas[pos].second) already++;
    
    al[pos][peg] = already + peg;

    if (already + peg > 2) return dp[pos][peg] = inf;
    if (pos == n-1) {
        return dp[pos][peg] = 2 - already - peg;
    }
    if (already + peg == 2) {
        return dp[pos][peg] = solve(pos + 1, 0);
    }
    else {
        if (canvas[pos].r == canvas[pos+1].l and !atPos[canvas[pos].r]) {
            dp[pos][peg] = min(solve(pos + 1, 1), solve(pos + 1, 0)) + (2 - already - peg);
        }
        else {
            dp[pos][peg] = solve(pos + 1, 0) + (2 - already - peg);
        }
        return dp[pos][peg];
    }

}



int main(){
    IO;
    cout<<fixed<<setprecision(2);
    
    memset(dp, -1, sizeof dp);
    cin >> n;

    canvas.resize(n+1);
    for (int i=0; i<n; i++) {
        cin >> canvas[i].first >> canvas[i].second;
    }   

    cin >> p;

    for (int i=0; i<p; i++) {
        int x;
        cin >> x;
        atPos[x] = true;
        pegs.push_back(x);
    }

    
    int x = solve(0, 0);
    if (x >= inf) {
        cout << "impossible" << endl;
    } 
    else {
        cout << x << endl;
        
        int peg = 0;
        for (int i=0; i<n; i++) {
            int req = 2 - al[i][peg];
            if (i == n-1 or dp[i][peg] == dp[i+1][0] + req) {
                peg = 0;
                vi place;
                for (int k=1; k<6; k++) {
                    if (atPos[canvas[i].l + k] == false) place.pb(canvas[i].l + k);
                }
                for (int k=0; k<req; k++) {
                    cout << place[k] << " ";
                }
            }
            else {
                peg = 1;
                vi place;
                for (int k=1; k<6; k++) {
                    if (atPos[canvas[i].l + k] == false) place.pb(canvas[i].l + k);
                }
                for (int k=0; k<req-1; k++) cout << place[k] << " ";
                cout << canvas[i].r << " ";
            }
        }
        cout << endl;

    }

}