#include <bits/stdc++.h>
#define re(x, y, z) for (int x=y; x<z; ++x)
#define trav(v, x) for (int v : x)
#define eb emplace_back
using namespace std;
const int maxn = 1e5 + 10;
long long h[maxn];
int lo[maxn], hi[maxn];
long long down[maxn];
using ii = pair<int, int>;
vector<ii> g[maxn];
int n, s, q, e;
ii edges[maxn];
bool shop[maxn];
const int LOG = 18;
int up[maxn][LOG];
long long st[maxn][LOG];
using lli = pair<long long, int>;
const long long inf = 1e18;
int T = 0;
int step[maxn];
void dfs(int x, int p, long long he) {
h[x] = he;
step[x] = step[p]+1;
lo[x] = T++;
down[x] = shop[x] ? 0 : inf;
for (auto node : g[x]) {
if (node.first == p) continue;
dfs(node.first, x, he + node.second);
down[x] = min(down[x], down[node.first] + node.second);
}
hi[x] = T++;
}
void dfs2(int x, int p) {
st[x][0] = down[x] - h[x];
up[x][0] = p==0?x:p;
for (int k = 1; k < LOG; ++k) {
st[x][k] = min(st[x][k-1], st[up[x][k-1]][k-1]);
up[x][k] = up[up[x][k-1]][k-1];
}
for (auto node : g[x]) {
if (node.first == p) continue;
dfs2(node.first, x);
}
}
bool isParent(int x, int y) {
return lo[x] <= lo[y] and hi[y] <= hi[x];
}
long long query(int x, int y) {
int len = step[x] - step[y] + 1;
long long ans = inf;
for (int k = 0; k < LOG; ++k) {
if (len & (1<<k)) {
ans = min(ans, st[x][k]);
x = up[x][k];
}
}
return ans;
}
int main() {
scanf("%d%d%d%d", &n, &s, &q, &e);
re(i, 1, n) {
int a, b, w;
scanf("%d%d%d", &a, &b, &w);
g[a].eb(b, w);
g[b].eb(a, w);
edges[i] = {a, b};
}
re(i, 0, s) {
int c;
scanf("%d", &c);
shop[c] = 1;
}
dfs(e, 0, 0);
dfs2(e, 0);
re(i, 0, q) {
int I, R;
scanf("%d%d", &I, &R);
int a = edges[I].first, b = edges[I].second;
if (h[a] > h[b]) swap(a, b);
if (isParent(b, R)) {
if (down[b] == inf) puts("oo");
else {
long long res = query(R, b) + h[R];
if (res >= inf) puts("oo");
else printf("%lld\n", res);
}
} else puts("escaped");
}
return 0;
}
