#include <bits/stdc++.h>
#define ll long long 
using namespace std;
const int N = 5e5 + 100;
int n;
struct dsu1{
    int fa[N];
    void init(){for(int i = 0;i <= n;i++) fa[i] = i;}
    int find(int x){return x == fa[x] ? x : (fa[x] = find(fa[x]));}
    bool merge(int x, int y){
        x = find(x), y = find(y);
        if(x == y) return 0;
        fa[x] = y;
        return 1;
    }
}ns, T;
vector<int> g[N];
int Fat[N];
struct Nod{
    ll s, val;
    int sz, id;
    bool operator < (const Nod &ot) const{
        return s * ot.sz > ot.s * sz;
    }
    Nod operator + (const Nod & ot) const{
        Nod ret;
        ret.s = s + ot.s;
        ret.sz = sz + ot.sz;
        ret.id = id;
        ret.val = val + ot.val + ot.s * sz;
        return ret;
    }
}Cur[N];
priority_queue<Nod> pq;
bool vis[N];
int main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n;ns.init();T.init();
    for(int i = 1;i <= n;i++){
        cin >> Fat[i];
        if(!ns.merge(i, Fat[i])){
            cout << "-1\n";
            return 0;
        }
    }
    Cur[0] = {0, 0, 0, 0};
    for(int i = 1, x;i <= n;i++){
        cin >> x;
        Cur[i] = {x, x, 1, i};
        pq.push(Cur[i]);
    }
    while(!pq.empty()){
        int u = pq.top().id;
        pq.pop();
        if(!u || vis[u]) continue;
        vis[u] = 1;
        int pt = T.find(Fat[u]);
        T.merge(u, Fat[u]);
        Cur[pt] = Cur[pt] + Cur[u];
        pq.push(Cur[pt]);
    }
    cout << Cur[0].val << endl;
    return 0;

}