#include <bits/stdc++.h>
using namespace std;
vector<int> g[200005];
int D;
int sub[200005], nn = 0;
int depth[200005];
bool vis[200005];
void dfs(int u, int p, int d) {
  depth[u] = d;
  for (int i = 0; i < g[u].size(); i++) {
    int v = g[u][i];
    if (v == p) continue;
    dfs(v, u, d + 1);
  }
}
void cal_sz(int u, int p) {
  nn++;
  sub[u] = 1;
  for (int i = 0; i < g[u].size(); i++) {
    int v = g[u][i];
    if (v == p || vis[v]) continue;
    cal_sz(v, u);
    sub[u] += sub[v];
  }
}
int find_centroid(int u, int p) {
  for (int i = 0; i < g[u].size(); i++) {
    int v = g[u][i];
    if (v == p || vis[v]) continue;
    if (sub[v] > nn / 2) return find_centroid(v, u);
  }
  return u;
}
void decompose(int u, int p) {
  nn = 0;
  cal_sz(u, 0);
  int c = find_centroid(u, 0);
  vis[c] = 1;
  int d;
  printf("d %d\n", c);
  fflush(stdout);
  scanf("%d", &d);
  if (d == 0) {
    printf("! %d\n", c);
    fflush(stdout);
    exit(0);
  }
  if (d + depth[c] == D) {
    int nt;
    printf("s %d\n", c);
    fflush(stdout);
    scanf("%d", &nt);
    for (int i = 0; i < g[c].size(); i++) {
      int v = g[c][i];
      if (v == p || vis[v]) continue;
      if (v == nt) decompose(nt, c);
    }
  } else {
    for (int i = 0; i < g[c].size(); i++) {
      int v = g[c][i];
      if (v == p || vis[v]) continue;
      if (depth[v] + 1 == depth[c]) {
        decompose(v, c);
        break;
      }
    }
  }
}
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 1; i < n; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    g[a].push_back(b);
    g[b].push_back(a);
  }
  dfs(1, 0, 0);
  printf("d 1\n");
  fflush(stdout);
  scanf("%d", &D);
  if (D == 0) {
    printf("! 1\n");
    return 0;
  }
  decompose(1, 0);
}
