1 #include<cstdio>
2 #include<cstring>
3 #include<algorithm>
4 #define MAXN 500010
5 using namespace std;
6 int x[MAXN];
7 bool vis[MAXN];
8 struct cmd
9 {
10 char s[6];
11 int val;
12 };
13 struct node
14 {
15 int left,right,val;
16 };
17 node tree[MAXN<<2];
18 cmd p[MAXN];
19 void Build(int L,int R,int rt)
20 {
21 tree[rt].left=tree[rt].right=-1;
22 tree[rt].val=0;
23 if(L!=R)
24 {
25 int mid=(L+R)>>1;
26 Build(L,mid,rt<<1);
27 Build(mid+1,R,rt<<1|1);
28 }
29 }
30 inline int MIN(int a,int b)
31 {
32 if(!a&&!b)
33 return 0;
34 if(!a)
35 return b;
36 if(!b)
37 return a;
38 return a>b?b:a;
39 }
40 inline void PushUp(int L,int R,int rt)
41 {
42 if(tree[rt<<1].left>=0)
43 tree[rt].left=tree[rt<<1].left;
44 else
45 tree[rt].left=tree[rt<<1|1].left;
46 if(tree[rt<<1|1].right>=0)
47 tree[rt].right=tree[rt<<1|1].right;
48 else
49 tree[rt].right=tree[rt<<1].right;
50 tree[rt].val=MIN(tree[rt<<1].val,tree[rt<<1|1].val);
51 if(tree[rt].left>=0&&tree[rt].right>=0)
52 tree[rt].val=MIN(tree[rt].val,x[tree[rt].right]-x[tree[rt].left]);
53 if(tree[rt<<1].right>=0&&tree[rt<<1|1].left>=0)
54 tree[rt].val=MIN(tree[rt].val,x[tree[rt<<1|1].left]-x[tree[rt<<1].right]);
55 }
56 void Update(int pos,bool flag,int L,int R,int rt)
57 {
58 if(L==R)
59 {
60 if(flag)
61 tree[rt].left=tree[rt].right=L;
62 else
63 tree[rt].left=tree[rt].right=-1;
64 }
65 else
66 {
67 int mid=(L+R)>>1;
68 if(pos<=mid)
69 Update(pos,flag,L,mid,rt<<1);
70 else
71 Update(pos,flag,mid+1,R,rt<<1|1);
72 PushUp(L,R,rt);
73 }
74 }
75 int main()
76 {
77 char s[6];
78 int n,i,cnt,size,pos;
79 while(~scanf("%d",&n))
80 {
81 memset(vis,false,sizeof(vis));
82 for(i=cnt=0;i<n;i++)
83 {
84 scanf(" %s",p[i].s);
85 if(p[i].s[0]!='m')
86 {
87 scanf("%d",&p[i].val);
88 x[cnt++]=p[i].val;
89 }
90 }
91 sort(x,x+cnt);
92 cnt=unique(x,x+cnt)-x;
93 Build(0,cnt-1,1);
94 for(i=size=0;i<n;i++)
95 {
96 if(p[i].s[0]=='a')
97 {
98 pos=lower_bound(x,x+cnt,p[i].val)-x;
99 if(!vis[pos])
100 {
101 vis[pos]=true;
102 size++;
103 Update(pos,true,0,cnt-1,1);
104 }
105 }
106 else if(p[i].s[0]=='d')
107 {
108 pos=lower_bound(x,x+cnt,p[i].val)-x;
109 if(vis[pos])
110 {
111 vis[pos]=false;
112 size--;
113 Update(pos,false,0,cnt-1,1);
114 }
115 }
116 else
117 {
118 if(size<2)
119 puts("0");
120 else
121 printf("%d\n",tree[1].val);
122 }
123 }
124 }
125 return 0;
126 }
