#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 5;
int n, len;
vector<int> way[maxn];
int h[maxn], leaf[maxn];
int have, cen;
int cnt[maxn], big[maxn];
int ban[maxn];
void dfs(int u, int last) {
  h[u] = h[last] + 1;
  if (h[u] == len + 1) leaf[u] = 1, have++;
  for (auto v : way[u])
    if (v != last) dfs(v, u);
}
void build(int u, int last) {
  cnt[u] = leaf[u];
  big[u] = 0;
  for (auto v : way[u]) {
    if (v == last || h[u] >= h[v] || ban[v]) continue;
    build(v, u);
    big[u] = max(big[u], cnt[v]);
    cnt[u] += cnt[v];
  }
  big[u] = max(big[u], have - cnt[u]);
  if (!leaf[u] && big[u] <= have / 2 + 1) cen = u;
}
int get(int u, int last) {
  if (leaf[u]) return u;
  for (auto v : way[u]) {
    if (v == last || h[u] >= h[v] || ban[v]) continue;
    int tmp = get(v, u);
    if (tmp) return tmp;
  }
  return 0;
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n - 1; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    way[u].push_back(v);
    way[v].push_back(u);
  }
  int CNT = 0;
  printf("d 1\n");
  fflush(stdout);
  CNT++;
  scanf("%d", &len);
  dfs(1, 0);
  int root = 1, last = 0;
  build(root, last);
  while (have > 1) {
    if (have == 2) {
      int tmp = get(root, last);
      printf("d %d\n", tmp);
      fflush(stdout);
      CNT++;
      int res;
      scanf("%d", &res);
      if (res != 0) ban[tmp] = 1;
      break;
    }
    int tmp = get(cen, 0);
    printf("d %d\n", tmp);
    fflush(stdout);
    CNT++;
    int res;
    scanf("%d", &res);
    if (res <= (h[tmp] - h[cen]) * 2) {
      printf("s %d\n", cen);
      fflush(stdout);
      CNT++;
      scanf("%d", &root);
      last = cen;
    } else
      ban[cen] = 1;
    build(root, last);
    have = cnt[root];
  }
  printf("! %d\n", get(root, last));
  fflush(stdout);
}
