#include<bits/stdc++.h>
#define ll long long    
#define ull unsigned long long
#define db double
#define ldb long double
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define FR first
#define SE second
using namespace std;
inline int read() {
  int x = 0; bool op = 0;
  char c = getchar();
  while(!isdigit(c))op |= (c == '-'), c = getchar();
  while(isdigit(c))x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
  return op ? -x : x;
}
const int N = 1e5 + 10;
int n;
int par[N], f[N], cnt[N];
struct Node {db c, p;}a[N];
bool operator < (Node x, Node y) {
  return x.c + y.c * x.p > y.c + x.c * y.p;
}
Node operator + (Node x, Node y) {
  return {x.c + x.p * y.c, x.p * y.p};
}
int find(int x) {return f[x] == x ? x : f[x] = find(f[x]);}
int main() { 
  n = read();
  priority_queue<pair<Node, pair<int, int>>> q;
  a[0] = {0, 1};
  for(int i = 1; i <= n; i++) {
    int d; db c, p;
    scanf("%lf%lf%d", &c, &p, &d);
    par[i] = d; f[i] = i; a[i] = {c, p}; 
    q.push({a[i], {i, 0}});
  }
  while(q.empty() == false) {
    auto x = q.top(); q.pop();
    if(x.SE.SE != cnt[x.SE.FR])continue;
    int u = x.SE.FR, p = find(par[u]);
    a[p] = a[p] + a[u]; f[u] = par[u];
    if(p)cnt[p]++, q.push({a[p], {p, cnt[p]}});
  }
  printf("%.10lf\n", a[0].c);
  return 0;
}