#include <algorithm>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <utility>

#define MAX 1000100
#define LC(x) ((x) << 1)
#define RC(x) (((x) << 1) | 1)
#define AVG(x, y) (((x) & (y)) + (((x) ^ (y)) >> 1))
#define PAR int x, int l, int r
#define LL LC(x), l, mid
#define RR RC(x), mid + 1, r

using namespace std;

struct SegTree {
    int val, sum;
} st[MAX << 2];

void pushUp(int x) {
    st[x].val = st[LC(x)].val == st[RC(x)].val ? st[LC(x)].val : -1;
    st[x].sum = st[LC(x)].sum + st[RC(x)].sum;
}

void pushDown(int x, int w) {
    if (~st[x].val) {
        st[LC(x)].val = st[RC(x)].val = st[x].val;
        st[LC(x)].sum = st[x].val * (w - (w >> 1));
        st[RC(x)].sum = st[x].val * (w >> 1);
    }
}

void build(PAR) {
    int mid = AVG(l, r);
    if (l == r) {
        st[x].val = st[x].sum = 0;
        return;
    }
    build(LL); build(RR);
    pushUp(x);
}

void update(PAR, int low, int high, int val) {
    int mid = AVG(l, r);
    if (low <= l && r <= high) {
        st[x].val = val;
        st[x].sum = val * (r - l + 1);
        return;
    }
    pushDown(x, r - l + 1);
    if (low <= mid) update(LL, low, high, val);
    if (high > mid) update(RR, low, high, val);
    pushUp(x);
}

int query(PAR, int low, int high) {
    int mid = AVG(l, r), ret = 0;
    if (low <= l && r <= high) return st[x].sum;
      pushDown(x, r - l + 1);
    if (low <= mid) ret += query(LL, low, high);
    if (high > mid) ret += query(RR, low, high);
    return ret;
}

#define L 32
#define X first
#define Y second

typedef pair<int, int> Pii;

char cmd[MAX][8], buf[MAX][L];
string str[MAX];

inline string MakeLast(const char* str) {
  string ret(str);
  ret.push_back('z' + 1);
  return ret;
}

int main() {
  int n;
  while (~scanf("%d", &n)) {
    for (int i = 0; i < n; ++i) {
      scanf("%s%s", cmd[i], buf[i]);
      str[i] = string(buf[i]);
    }
    sort(str, str + n);
    int m = unique(str, str + n) - str;
    build(1, 0, m - 1);
    for (int i = 0; i < n; ++i) {
      if (cmd[i][0] == 'i') {
        int p = lower_bound(str, str + m, string(buf[i])) - str;
        int cur = query(1, 0, m - 1, p, p);
        update(1, 0, m - 1, p, p, cur + 1);
      } else if (cmd[i][0] == 'd') {
        int l = lower_bound(str, str + m, string(buf[i])) - str;
        int r = lower_bound(str, str + m, MakeLast(buf[i])) - str - 1;
        update(1, 0, m - 1, l, r, 0);
      } else if (cmd[i][0] == 's') {
        int l = lower_bound(str, str + m, string(buf[i])) - str;
        int r = lower_bound(str, str + m, MakeLast(buf[i])) - str - 1;
        int cur = query(1, 0, m - 1, l, r);
        printf("%s\n", cur ? "Yes" : "No");
      }
    }
  }
  return 0;
}