#include <bits/stdc++.h>

using namespace std;

const int BUFFER_SIZE = 1 << 20;
char rb[BUFFER_SIZE], *rp = rb, *rt = rb;
inline char read_char() {
    return rp == rt ? (rt = rb + fread(rb, 1, BUFFER_SIZE, stdin), rp = rb, *rp ++) : *rp ++;
}
inline int read_int() {
    int x = 0;
    char ch = read_char(), flag = 0;
    while (ch != '-' && (ch < '0' || ch > '9')) {
        ch = read_char();
    }
    if (ch == '-') {
        flag = 1;
        ch = read_char();
    }
    for (x = 0; ch >= '0' && ch <= '9'; ch = read_char()) {
        x = x * 10 + (ch - '0');
    }
    return flag ? -x : x;
}
inline int read_string(char* s) {
    char* s0 = s;
    for (char ch = read_char(); ch > ' '; ch = read_char()) {
        *s ++ = ch;
    }
    return s - s0;
}

char wb[BUFFER_SIZE], *wp = wb;
inline void write_flush() {
    fwrite(wb, 1, wp - wb, stdout);
    wp = wb;
}
inline void write_char(char c) {
    *wp ++ = c;
    if (wp == wb + BUFFER_SIZE) {
        write_flush();
    }
}
inline void write_string(const char* s) {
    for (; *s; s ++) {
        write_char(*s);
    }

}

const int MAX_N = 500000 + 5;
typedef long long i64;

int N;
int a[MAX_N], f[MAX_N];
i64 w[MAX_N], c[MAX_N], ans;
vector<int> son[MAX_N];
struct Node {
    i64 w, c;
    int i;
    bool operator < (const Node &t) const {
        return w * t.c > t.w * c;
    }
};
priority_queue<Node> pq;

int get_fath(int i) {
    return f[i] == i ? i : f[i] = get_fath(f[i]);
}

int main() {
    N = read_int();
    for (int i = 1; i <= N; i ++) {
        a[i] = read_int();
        
        f[i] = i;
    }
    for (int i = 1; i <= N; i ++) {
        w[i] = read_int();
        c[i] = 1;
        ans += w[i];
        pq.push((Node){w[i], c[i], i});
    }
    while (pq.size()) {
        auto tmp = pq.top();
        pq.pop();
        int i = tmp.i;
        if (c[i] != tmp.c) continue;
        if (!a[i]) continue;
        int j = get_fath(a[i]);
        if (j == i) {
            printf("-1\n");
            return 0;
        }
        if (w[i] * c[j] < w[j] * c[i]) {
            ans += c[j] * w[i];
            f[i] = j;
            w[j] += w[i];
            c[j] += c[i];
            pq.push((Node){w[j], c[j], j});
        }
    }
    for (int i = 1; i <= N; i ++) {
        if (f[i] != i) continue;
        pq.push((Node){w[i], c[i], i});
    }
    while (pq.size()) {
        auto tmp = pq.top();
        pq.pop();
        int i = tmp.i;
        int j = get_fath(a[i]);
        ans += c[j] * w[i];
        f[i] = j;
        w[j] += w[i];
        c[j] += c[i];
    }
    printf("%lld\n", ans);
    return 0;
}