#include<bits/stdc++.h>
using namespace std;
#define N 100005
int tin[N],tout[N],depp[N],bp[20][N],t;
long long dp[N],dep[N],mi[20][N],ans;
pair<int,int> edge[N];
vector<pair<int,long long>> g[N];
// dp[i] lowest shop in i subtree
void dfs(int s,int f){
tin[s]=++t;
if(dp[s]==-1)dp[s]=dep[s];
for(auto [x,w]:g[s]){
if(x==f)continue;
dep[x]=dep[s]+w;
dfs(x,s);
dp[s]=min(dp[s],dp[x]);
}
tout[s]=t;
}
void dfs2(int s,int f){
depp[s]=depp[f]+1;
bp[0][s]=f;
mi[0][s]=dp[f]-2*dep[f];
for(auto [x,w]:g[s]){
if(x==f)continue;
dfs2(x,s);
}
}
int main(){
int n,s,q,e,a,b,i,j,k,idx,r;
long long w;
scanf("%d %d %d %d",&n,&s,&q,&e);
for(i=1;i<n;i++){
scanf("%d %d %lld",&a,&b,&w);
g[a].push_back({b,w});
g[b].push_back({a,w});
edge[i]={a,b};
dp[i]=1e18;
}
dp[n]=1e18;
for(i=1;i<=s;i++){
scanf("%d",&k);
dp[k]=-1;
}
dfs(e,0);
dfs2(e,0);
for(i=1;i<20;i++)for(j=1;j<=n;j++)bp[i][j]=bp[i-1][bp[i-1][j]],mi[i][j]=min(mi[i-1][j],mi[i-1][bp[i-1][j]]);
while(q--){
scanf("%d %d",&idx,&r);
auto [a,b]=edge[idx];
a=(depp[a]>depp[b])?a:b;
if(tin[a]<=tin[r]&&tin[r]<=tout[a]){
int dif=depp[r]-depp[a],temp=r;
ans=dp[r]-dep[r];
for(i=0;i<20;i++)if(dif&(1<<i))ans=min(ans,dep[r]+mi[i][temp]),temp=bp[i][temp];
if(ans>1e16)printf("oo\n");
else printf("%lld\n",ans);
}
else printf("escaped\n");
}
return 0;
}
