#include <vector>#include <map>#include <set>#include <deque>#include <stack>#include <bitset>#include <algorithm>#include <sstream>#include <iostream>#include <cstdio>#include <queue>#include <cmath>#include <cstdlib>#include <cstring>#include <ctime>#include <string>#include <cassert>using namespace std;#define fr(i,n) for(i=0;i<n;i++)#define fro(i,a,n) for(i=a;i<=n;i++)#define pb push_back#define inf 200000000#define maxn 512int f_max(int x,int y){return x>y?x:y;}int f_min(int x,int y){return x<y?x:y;}int f_abs(int x){if(x>0) return x;return -x;}void swap(int &x,int &y){int t;t=x,x=y,y=t;}int del[maxn][maxn];int vis[maxn],flag;struct po{ char s[2]; int u,v;}a[65536];int mid,uu,vv;set<int>g[maxn];bool f(int u,int v){ if(u==v) return true; set<int>::iterator it; vis[u]=flag; for(it=g[u].begin();it!=g[u].end();it++){ int i=(*it); if(vis[i]==flag) continue; if( f(i,v) ) { if(del[i][u] < mid) { mid=del[i][u],uu=i,vv=u; } return true; } } return false;}int main(){ int i,j,n,m,u,v; int cas=0; while(~scanf("%d%d",&n,&m)){ fro(i,1,n) fro(j,1,n) del[i][j]=inf; fro(i,1,n) g[i].clear(),vis[i]=-1; fr(i,m){ scanf("%s %d %d",a[i].s,&a[i].u,&a[i].v); if(a[i].s[0]=='D'){ del[a[i].u][a[i].v]=del[a[i].v][a[i].u]=i; } } if(cas>0) printf("n"); printf("Case %d:n",++cas); fr(i,m){ flag=i; u=a[i].u; v=a[i].v; mid=inf; if(a[i].s[0]=='I'){ if(f(u,v)){ if(mid<del[u][v]){ g[uu].erase(vv); g[vv].erase(uu); g[u].insert(v); g[v].insert(u); } } else{ g[u].insert(v); g[v].insert(u); } } else if(a[i].s[0]=='D'){ g[u].erase(v); g[v].erase(u); } else{ if(f(u,v)) printf("YESn"); else printf("NOn"); } } } return 0;}
