#include <bits/stdc++.h>
using namespace std;
#define MAXN 100005
#define INF 10000000000000000ll
int n, s, q, r;
vector<pair<int, long long>> adj[MAXN];
pair<int, int> edges[MAXN];
int tin[MAXN], tout[MAXN];
long long sumDepth[MAXN];
int depth[MAXN];
int curtime = 0;
int up[MAXN][32];
long long minUp[MAXN][32];
long long dp[MAXN];
bool isShop[MAXN];
void dfs(int v, int p = -1, long long d = 0, int dd = 0){
sumDepth[v] = d;
depth[v] = dd;
tin[v] = ++curtime;
dp[v] = INF;
up[v][0] = p;
for(int i = 1; i<32 && up[v][i-1] != -1; i++) up[v][i] = up[up[v][i-1]][i-1];
for(auto u : adj[v]){
if(u.first == p) continue;
dfs(u.first, v, d+u.second, dd+1);
dp[v] = min(dp[v], dp[u.first]+u.second);
}
if(isShop[v]) dp[v] = 0;
tout[v] = ++curtime;
}
void getMinUp(int v, int p = -1){
if(p == -1) minUp[v][0] = INF;
else minUp[v][0] = dp[p]-sumDepth[p];
for(int i = 1; i<32 && up[v][i-1] != -1; i++) minUp[v][i] = min(minUp[v][i-1], minUp[up[v][i-1]][i-1]);
for(auto u : adj[v]){
if(u.first == p) continue;
getMinUp(u.first, v);
}
}
bool isPar(int a, int b){
return tin[a] <= tin[b] && tout[a] >= tout[b];
}
long long query(int v, int h){
long long ans = INF;
for(int i = 30; i>=0; i--){
if((1<<i) <= h){
ans = min(ans, minUp[v][i]);
// cout << (1<<i) << endl;
v = up[v][i];
h -= (1<<i);
}
}
return ans;
}
int main(){
// freopen("a.in", "r", stdin);
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n >> s >> q >> r;
--r;
for(int i = 0; i<n-1; i++){
int a, b; cin >> a >> b;
--a; --b;
int w; cin >> w;
adj[a].push_back({b, w});
adj[b].push_back({a, w});
edges[i] = {a, b};
}
for(int i = 0; i<s; i++){
int a; cin >> a; --a;
isShop[a] = 1;
}
dfs(r);
getMinUp(r);
while(q--){
int ind, v; cin >> ind >> v;
--ind; --v;
int a = edges[ind].first, b = edges[ind].second;
if(depth[a] < depth[b]) swap(a, b);
if(!(isPar(a, v) && isPar(b, v))){
cout << "escaped" << endl;
continue;
}
// cout << query(v, depth[v]-depth[a]) << endl;
long long ans = sumDepth[v]+min(dp[v]-sumDepth[v], query(v, depth[v]-depth[a]));
if(ans >= INF/2) cout << "oo" << endl;
else cout << ans << endl;
}
}
