#include <bits/stdc++.h>
using namespace std;
vector<int> G[200005];
int st[200005];
int vis[200005];
int totalSize, distVCent;
int D[200005];
int query(char op, int v) {
  int ret;
  printf("%c %d\n", op, v);
  fflush(stdout);
  scanf("%d", &ret);
  return ret;
}
void ans(int v) {
  printf("! %d\n", v);
  exit(0);
}
void calc_subtree(int v, int p) {
  st[v] = 1;
  for (int x : G[v]) {
    if (x == p or vis[x]) continue;
    calc_subtree(x, v);
    st[v] += st[x];
  }
}
int find_centroid(int v, int p) {
  for (int x : G[v]) {
    if (x == p or vis[x]) continue;
    if (st[x] * 2 >= totalSize) return find_centroid(x, v);
  }
  return v;
}
void dist(int cur, int destiny, int p, int d) {
  if (cur == destiny) distVCent = d;
  for (int x : G[cur]) {
    if (x == p or vis[x]) continue;
    dist(x, destiny, cur, d + 1);
  }
}
void centroid(int v) {
  int distRoot = (D[v] == -1) ? query('d', v) : D[v];
  D[v] = distRoot;
  if (distRoot == 0) {
    ans(v);
  }
  calc_subtree(v, 0);
  totalSize = st[v];
  if (totalSize == 1) {
    ans(v);
  }
  int cent = find_centroid(v, 0);
  int distCentroid = D[cent] == -1 ? query('d', cent) : D[cent];
  D[cent] = distCentroid;
  if (distCentroid == 0) {
    ans(cent);
  }
  dist(v, cent, 0, 0);
  vis[cent] = 1;
  if (distCentroid > distRoot) {
    centroid(v);
  } else if (distVCent + distCentroid == distRoot) {
    int nxt = query('s', cent);
    D[nxt] = distCentroid - 1;
    centroid(nxt);
  } else {
    centroid(v);
  }
}
int main() {
  int n, a, b;
  scanf("%d", &n);
  for (int i = 1; i < n; i++) {
    scanf("%d%d", &a, &b);
    G[a].push_back(b);
    G[b].push_back(a);
  }
  memset(D, -1, sizeof D);
  centroid(1);
  return 0;
}
