#include <bits/stdc++.h>
using namespace std;
#define ar array
#define int long long
#define ld long double
#define crash assert(69 == 420)
const int MOD = 1e9 + 7;
const int INF = 1e17;
const int N = 2e5 + 20;
const int LOG = 20;
int n, k, q, r;
vector<ar<int, 2>> g[N];
int in[N], out[N], T = -1;
int dep[N],dst[N], dp[N];
int up[N][LOG], mn[N][LOG];
void dfs(int x,int p){
in[x] = ++T;
for(auto [u, w]: g[x]){
if(u == p)continue;
dep[u] = dep[x] + 1;
dst[u] = dst[x] + w;
dfs(u, x);
dp[x] = min(dp[x], dp[u] + w);
}
out[x] = T;
up[x][0] = p;
if(dp[x] < INF)mn[x][0] = min(mn[x][0], dp[x] - dst[x]);
}
bool anc(int u,int v){
return in[u] <= in[v] && out[v] <= out[u];
}
int qry(int u,int k){
int ans = INF;
for(int i = 0;i < LOG;i++){
if((1 << i) & k){
ans = min(ans, mn[u][i]);
u = up[u][i];
}
}
return ans;
}
signed main(){ios_base::sync_with_stdio(false);cin.tie(0);
cin>>n>>k>>q>>r;
--r;
ar<int, 2> e[n];
for(int i = 1;i < n;i++){
int u, v, w;
cin>>u>>v>>w;
--u, --v;
e[i] = {u, v};
g[u].push_back({v, w});
g[v].push_back({u, w});
}
for(int i = 0;i < n;i++)dp[i] = mn[i][0] = INF;
while(k--){
int x;
cin>>x;
--x;
dp[x] = 0;
}
dfs(r, r);
for(int j = 1;j < LOG;j++){
for(int i = 0;i < n;i++){
up[i][j] = up[up[i][j - 1]][j - 1];
mn[i][j] = min(mn[i][j - 1], mn[up[i][j - 1]][j - 1]);
}
}
while(q--){
int i, p;
cin>>i>>p;
--p;
if(dep[e[i][0]] < dep[e[i][1]])swap(e[i][0], e[i][1]);
if(!anc(e[i][0], p)){
cout<<"escaped\n";
continue;
}
int ans = dst[p] + qry(p, dep[p] - dep[e[i][0]] + 1);
if(ans >= INF)cout<<"oo\n";
else cout<<ans<<'\n';
}
}
