#include<bits/stdc++.h>
#define lowbit(x) (x&-x)
#define sum(l,r) (ask(r)-ask(l-1))
using namespace std;
int read() {
register int x=1,ans=0;register char ch=getchar();
while(ch<'0'||ch>'9') {if(ch=='-') x*=-1;ch=getchar();}
while(ch>='0'&&ch<='9') {ans=(ans<<3)+(ans<<1)+ch-48;ch=getchar();}
return x*ans;
}
const int N=50005;
int c[N],n,m;
void add(int x,int val) {
for(;x<=n;x+=lowbit(x)) c[x]+=val;
}
int ask(int x) {
int ans=0;
for(;x>=1;x-=lowbit(x)) ans+=c[x];
return ans;
}
int main() {
n=read(); m=read();
for(register int i=1;i<=n;++i) add(i,1);
stack<int> w;
while(m--) {
char ch; cin>>ch;
if(ch=='D') {
int x=read();
add(x,-1);
w.push(x);
}
else if(ch=='R') {
int x=w.top(); w.pop(); add(x,1);
}
else {
int x=read();
if(sum(x,x)==0) puts("0");
else {
int l=1,r=x,res=0;
while(l<=r) {
int mid=(l+r)>>1;
if(sum(mid,x)==x-mid+1) res=mid,r=mid-1;
else l=mid+1;
}
int ll=res;
l=x,r=n;
while(l<=r) {
int mid=(l+r)>>1;
if(sum(x,mid)==mid-x+1) res=mid,l=mid+1;
else r=mid-1;
}
int rr=res;
printf("%dn",rr-ll+1);
}
}
}
return 0;
}
2026-01-27 03:44:14
极好的 旅游专栏, 继续发展 保持节奏。谢谢. [url=https://iqvel.com/zh-Hans/a/%E5%8D%B0%E5%BA%A6/Vaishno-Devi]恆卡爾考洞窟[/url] 令人愉快的 旅游杂志, 请继续 保持这种风格。多谢.
