#define  _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <iomanip>
#include <queue>
using namespace std;
//构造一棵树结构，使用BFS处理每个节点的深度，然后遍历每个子节点进行统计
class node {
public :
    int father;
    vector<int> son;
    int level;
} supply_train[100005];
int node_level[100005];
vector< pair<int, int> > retails;

void calculate_level() {
    int i;
    queue<int> q;
    q.push( 0 );
    node_level[0] = 0;

    while ( !q.empty() ) {
        int cur = q.front();
        q.pop();

        for ( i = 0; i < supply_train[cur].son.size(); i++ ) {
            node_level[supply_train[cur].son[i]] = node_level[cur] + 1;
            q.push( supply_train[cur].son[i] );
        }
    }
}


int main() {
    int n, i, e, j, id, amount;
    double p, r;
    scanf( "%d %lf %lf", &n, &p, &r );
    r /= 100.;

    for ( i = 0; i < n; i++ ) {
        scanf( "%d", &e );

        if ( e ) {
            for ( j = 0; j < e; j++ ) {
                scanf( "%d", &id );
                supply_train[i].son.push_back( id );
                supply_train[id].father = i;
            }
        } else {
            scanf( "%d", &amount );
            retails.push_back( make_pair( i, amount ) );
        }
    }

    calculate_level();
    double ans = 0.0;

    for ( i = 0; i < retails.size(); i++ )
        ans += p * pow( ( 1 + r ), node_level[ retails[i].first ] ) * retails[i].second;

    printf( "%.1lf\n", ans );
    return 0;
}