#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+7;
struct edge{
    int x;
    long long cost;
    edge(int _x=0,long long _c=0ll):x(_x),cost(_c){}
    void read(){
        scanf("%d %lld",&x,&cost);
    }
};
edge l[N],r[N];
edge p[N];
int main(){
//freopen("input.txt","r",stdin);
    int n;
    cin>>n;
    for(int i=1;i<=n;++i){
        l[i].read();
        r[i].read();
        if(l[i].x!=0){
            p[l[i].x]=edge(i,l[i].cost);
        }
        if(r[i].x!=0){
            p[r[i].x]=edge(i,r[i].cost);
        }
    }
    int v;
    cin>>v;
    long long ans=0;
    while(true){
        if(p[v].x==0){
            break;
        }
        int ls=v;
        v=p[v].x;
        if(ans+1>p[ls].cost){
            cout<<-1<<endl;
            return 0;
        }
        if(ls==r[v].x){
            ans+=max(l[v].cost-(r[v].cost-ans)+1ll,0ll);
        }
        else{
            ans+=max(r[v].cost-(l[v].cost-ans),0ll);
        }
    }
    cout<<ans+1<<endl;
    return 0;
}