简单线段树。。。更新的时候就单点更新。。查询的时候就查询x点左右最近的有破坏的点就行了。。
#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 50005
#define maxm 40005
#define eps 1e-10
#define mod 1000000007
#define INF 999999999
#define lowbit(x) (x&(-x))
#define mp mark_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
typedef long long LL;
//typedef int LL;
using namespace std;
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head
int sum[maxn<<2];
char ss[maxn];
stack<int> s;
int ql, qr, n, m, p, v, ans1, ans2;
void pushup(int o)
{
if(sum[ls] || sum[rs]) sum[o] = 1;
else sum[o] = 0;
}
void updata(int o, int L, int R)
{
if(L == R) {
sum[o] = v;
return;
}
int mid = (L+R)>>1;
if(p <= mid) updata(lson);
else updata(rson);
pushup(o);
}
void query1(int o, int L, int R)
{
if(ans1) return;
if(L == R && sum[o]) {
ans1 = L;
return;
}
int mid = (L+R)>>1;
if(ql <= L && qr >= R) {
if(!sum[o]) return;
if(sum[rs]) query1(rson);
else query1(lson);
}
if(qr > mid) query1(rson);
if(ql <= mid) query1(lson);
}
void query2(int o, int L, int R)
{
if(ans2) return;
if(L == R && sum[o]) {
ans2 = L;
return;
}
int mid = (L+R)>>1;
if(ql <= L && qr >= R) {
if(!sum[o]) return;
if(sum[ls]) query2(lson);
else query2(rson);
}
if(ql <= mid) query2(lson);
if(qr > mid) query2(rson);
}
void work(void)
{
int x;
while(!s.empty()) s.pop();
memset(sum, 0, sizeof sum);
p = 1, v = 1, updata(1, 1, n+2);
p = n+2, v = 1, updata(1, 1, n+2);
while(m--) {
scanf("%s", ss);
if(ss[0] == 'R') {
p = s.top(), s.pop(), v = 0;
updata(1, 1, n+2);
}
if(ss[0] == 'D') {
scanf("%d", &p);
s.push(++p), v = 1;
updata(1, 1, n+2);
}
if(ss[0] == 'Q') {
scanf("%d", &x);
ans1 = ans2 = 0;
ql = 1, qr = ++x;
query1(1, 1, n+2);
ql = x, qr = n+2;
query2(1, 1, n+2);
if(ans1 == ans2) printf("0\n");
else printf("%d\n", ans2 - ans1 - 1);
}
}
}
int main(void)
{
while(scanf("%d%d", &n, &m)!=EOF) work();
return 0;
}
