#include <iostream>
#include <algorithm>

typedef long long ll;
typedef double lf;

// #define DEBUG 1
struct IO
{
    #define MAXSIZE (1 << 20)
    #define isdigit(x) (x >= '0' && x <= '9')
    char buf[MAXSIZE], *p1, *p2;
    char pbuf[MAXSIZE], *pp;
    #if DEBUG
    #else
    IO() : p1(buf), p2(buf), pp(pbuf) {}
    ~IO() {fwrite(pbuf, 1, pp - pbuf, stdout);}
    #endif
    #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
    #define blank(x) (x == ' ' || x == '\n' || x == '\r' || x == '\t')

    template <typename T>
    void Read(T &x)
    {
        #if DEBUG
        std::cin >> x;
        #else
        bool sign = 0; char ch = gc(); x = 0;
        for (; !isdigit(ch); ch = gc())
            if (ch == '-') sign = 1;
        for (; isdigit(ch); ch = gc()) x = x * 10 + (ch ^ 48);
        if (sign) x = -x;
        #endif
    }
    void Read(char *s)
    {
        #if DEBUG
        std::cin >> s;
        #else
        char ch = gc();
        for (; blank(ch); ch = gc());
        for (; !blank(ch); ch = gc()) *s++ = ch;
        *s = 0;
        #endif
    }
    void Read(char &c) {for (c = gc(); blank(c); c = gc());}

    void Push(const char &c)
    {
        #if DEBUG
        putchar(c);
        #else
        if (pp - pbuf == MAXSIZE) fwrite(pbuf, 1, MAXSIZE, stdout), pp = pbuf;
        *pp++ = c;
        #endif
    }
    template <typename T>
    void Write(T x)
    {
        if (x < 0) x = -x, Push('-');
        static T sta[35];
        int top = 0;
        do sta[top++] = x % 10, x /= 10; while (x);
        while (top) Push(sta[--top] ^ 48);
    }
    template <typename T>
    void Write(T x, char lst) {Write(x), Push(lst);}
} IO;
#define Read(x) IO.Read(x)
#define Write(x, y) IO.Write(x, y)
#define Put(x) IO.Push(x)

using namespace std;

const int MAXN = 65;

int n;

struct seg
{
    int l, r;
    bool operator < (const seg &u) const { return r < u.r; }
}a[MAXN];

ll f[MAXN][MAXN];

ll ans = -1e12, w[MAXN];
void DFS(int u, ll val, ll vis, ll avl)
{
    int m = n - __builtin_popcountll(vis);
    if (u > m) return !m && (ans = max(ans, val)), void();
    if (f[u][m] + val < ans) return;
    ll navl = 0;
    for (int i = 1; i <= n; i++)
    {
        if (((avl >> i - 1) & 1) && a[i].r < u)
        {
            if (!((vis >> i - 1) & 1)) return;
        }
        else if (!((avl >> i - 1) & 1) && a[i].l == u) navl ^= (1ll << i - 1);
        else navl ^= avl & (1ll << i - 1);
    }
    DFS(u + 1, val, vis, navl);
    ll nvis = vis; int ct = 0;
    for (int i = 1; i <= n; i++)
        if (!((vis >> i - 1) & 1) && ((navl >> i - 1) & 1))
            ct++;
    ct /= u;
    for (int i = 1, j = 1, cc; i <= ct; i++)
    {
        cc = u, val += w[u];
        for (; cc; j++)
            if (!((vis >> j - 1) & 1) && ((navl >> j - 1) & 1))
                nvis ^= (1ll << j - 1), cc--;
        DFS(u + 1, val, nvis, navl);
    }
}

int main()
{
    #if DEBUG
    #else
    ios::sync_with_stdio(0), cin.tie(0);
    #endif
    Read(n);
    for (int i = 1; i <= n; i++) Read(a[i].l), Read(a[i].r);
    for (int i = 1; i <= n; i++) Read(w[i]);


    for (int j = 1; j <= n; j++)
        f[n + 1][j] = -1e18;
    for (int i = n; i >= 1; i--)
    {
        for (int j = 0; j <= n; j++)
            f[i][j] = f[i + 1][j];
        for (int j = i; j <= n; j++)
            if (f[i + 1][j - i] != -1e18)
                f[i][j] = max(f[i][j], f[i + 1][j - i] + w[i]);
    }

    sort(a + 1, a + n + 1);
    DFS(1, 0, 0, 0);
    if (ans == -1e12) cout << "impossible\n";
    else cout << ans << "\n";
    return 0;
}