[NOI2004]郁闷的出纳员

#include<cstdio>
#include<iostream>
using namespace std;
int delta, n, m, leave;
struct Treap{
struct Node{
int v, r, s;
Node* ch[2];
int cmp(int x) const{
if(x == v) return -1;
else return x < v ? 0 : 1;
}
void maintain(){
s = ch[0]->s + ch[1]->s +1;
}
};
Node *root, *null;
Treap(){
null = new Node();
root = null;
}
void rotate(Node* &o, int d){
Node* k = o->ch[d^1];
o->ch[d^1] = k->ch[d];
k->ch[d] = o;
o->maintain();
k->maintain();
o = k;
}
void insert(Node* &o, int x){
if(o == null){
o = new Node();
o->ch[0] = o->ch[1] = null;
o->v = x;
o->r = rand();
o->s = 1;
}
else{
int d = (x < o->v ? 0 : 1);
insert(o->ch[d], x);
if(o->ch[d]->r > o->r) rotate(o, d^1);
}
o->maintain();
}
int del(Node* &o, int x){
if(o == null) return 0;
if(o->v < x){
int t = o->ch[0]->s + 1;
o = o->ch[1];
return t + del(o, x);
}
else{
int t = del(o->ch[0], x);
o->s -= t;
return t;
}
}
int find(Node* o, int k){
if(o == null || k <= 0 || k > o->s) return 0;
int s = (o->ch[1] == null ? 0 : o->ch[1]->s);
if(s + 1 == k) return o->v;
if(s >= k) return find(o->ch[1], k);
return find(o->ch[0], k-s-1);
}
} tp;

int main(){
//freopen("p1503.in", "r", stdin);
scanf("%d %d\n", &n, &m);
char p[10];
int x;
tp = Treap();
while(n--){
scanf("%s%d\n", p, &x);
if(p[0] == 'I') if(x >= m) tp.insert(tp.root, x-delta);
if(p[0] == 'A') delta += x;
if(p[0] == 'S'){ delta -= x; leave += tp.del(tp.root, m-delta); }
if(p[0] == 'F'){
if(x > tp.root->s) printf("-1\n");
else printf("%d\n", tp.find(tp.root, x)+delta);
}
}
printf("%d\n", leave);
return 0;
}