#include<bits/stdc++.h>
#define taskname "landslide"
using namespace std;
typedef long long ll;
template<class T>void minimize(T& a, T b){
if(a > b){
a = b;
}
}
const ll INF = 1e18;
const int lim = 1e5 + 5;
int t_dfs = 0, U[lim], V[lim], W[lim], low[lim], tail[lim], up[lim][17];
ll dp[lim][17], f[lim];
vector<int>g[lim];
bitset<lim>mark;
void dfs_1(int s, int p = -1){
if(mark.test(s)){
dp[s][0] = 0;
}
low[s] = ++t_dfs;
for(int& i : g[s]){
int d = U[i] ^ V[i] ^ s;
if(d != p){
int w = W[i];
f[d] = f[up[d][0] = s] + w;
for(int i = 1; i < 17; i++){
up[d][i] = up[up[d][i - 1]][i - 1];
}
dfs_1(d, s);
minimize(dp[s][0], dp[d][0] + w);
}
}
tail[s] = t_dfs;
}
void dfs_2(int s, int p = -1){
dp[s][0] -= f[s];
for(int i = 1; i < 17; i++){
dp[s][i] = min(dp[s][i - 1], dp[up[s][i - 1]][i - 1]);
}
for(int& i : g[s]){
int d = U[i] ^ V[i] ^ s;
if(d != p){
dfs_2(d, s);
}
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if(fopen(taskname".inp", "r")){
freopen(taskname".inp", "r", stdin);
}
int n, s, q, h;
cin >> n >> s >> q >> h;
for(int i = 1; i < n; i++){
cin >> U[i] >> V[i] >> W[i];
g[U[i]].emplace_back(i);
g[V[i]].emplace_back(i);
}
mark.reset();
for(int i = 0; i < s; i++){
int x;
cin >> x;
mark.set(x);
}
memset(dp, 0x0f, sizeof(dp));
memset(up, 0, sizeof(up));
dfs_1(h);
dfs_2(h);
for(int _ = 0; _ < q; _++){
int I, R;
cin >> I >> R;
int u = U[I], v = V[I];
if(low[u] > low[v]){
swap(u, v);
}
if(low[v] <= low[R] && tail[v] >= low[R]){
ll ans = INF, temp = f[R];
for(int i = 16; i > -1; i--){
int ances = up[R][i];
if(ances != 0 && low[v] <= low[ances] && tail[v] >= low[ances]){
minimize(ans, dp[R][i]);
R = ances;
}
}
minimize(ans, dp[R][0]);
if(ans + temp > ll(1e16)){
cout << "oo\n";
continue;
}
cout << ans + temp << "\n";
}
else{
cout << "escaped\n";
}
}
}
