#include using namespace std; #define modulo 998244353 #define mod(mod_x) ((((long long)mod_x+modulo))%modulo) #define Inf 1000000000000000000 int beki(long long a,long long b,int M = modulo){ int x = 1; while(b!=0){ if(b&1){ x=((long long)x*a)%M; } a=((long long)a*a)%M; b>>=1; } return x; } int gyakugen(int a){ return beki(a,modulo-2); } struct combi{ deque kaijou; deque kaijou_; combi(int n){ kaijou.push_back(1); for(int i=1;i<=n;i++){ kaijou.push_back(mod(kaijou[i-1]*i)); } int b=gyakugen(kaijou[n]); kaijou_.push_front(b); for(int i=1;i<=n;i++){ int k=n+1-i; kaijou_.push_front(mod(kaijou_[0]*k)); } } int combination(int n,int r){ if(r>n)return 0; int a = mod(kaijou[n]*kaijou_[r]); a=mod(a*kaijou_[n-r]); return a; } int junretsu(int a,int b){ int x = mod(kaijou_[a]*kaijou_[b]); x=mod(x*kaijou[a+b]); return x; } int catalan(int n){ return mod(combination(2*n,n)*gyakugen(n+1)); } }; int N,M; combi C(1000000); int get(int n,int b){ static vector> dp(100005,vector(18,-1)); if(dp[n][b]!=-1)return dp[n][b]; int sum = 0; if(b>=1){ for(int i=0;i<=n;i++){ if(N-n + i < 3)continue; int t = C.combination(n,i)*C.kaijou[b+i]; t = mod(t * gyakugen(b+i)); sum = mod(sum +t); } int ret = mod(sum*beki(2,max(0,b-1))); dp[n][b] = ret; return ret; } else{ int ret =0; for(int i=3;i<=n;i++){ int t = mod(C.combination(n,i) * C.kaijou[i]); t = mod(t * gyakugen(2)); t = mod(t * gyakugen(i)); ret = mod(ret + t); } dp[n][b] = ret; return ret; } } bool check(vector> p){ int now = p[0].second; int goal = p[0].first; p.erase(p.begin()); for(int i=0;i<30;i++){ for(int j=0;j>N>>M; vector> p(M); for(int i=0;i>p[i].first>>p[i].second; p[i].first--; p[i].second--; if(p[i].first>p[i].second)swap(p[i].first,p[i].second); } int ans = 0; for(int i=0;i<(1<> q; int cnt = 0; map mp; for(int j=0;j>j)&1){ mp[p[j].first]++; mp[p[j].second]++; q.push_back(p[j]); cnt++; } } bool f = true; int c1 = 0; for(auto a:mp){ if(a.second>=3){ f=false; break; } if(a.second==1){ c1++; } } if(!f)continue; int t; if(c1==0&&mp.size()!=0){ if(!check(q))continue; t = 1; } else{ t = get(N-mp.size(),c1/2); } if(cnt%2==0)ans = mod(ans + t); else ans =mod(ans - t); } cout<