//STATUS:C++_AC_390MS_996KB

 #include <functional>

 #include <algorithm>

 #include <iostream>

 //#include <ext/rope>

 #include <fstream>

 #include <sstream>

 #include <iomanip>

 #include <numeric>

 #include <cstring>

 #include <cassert>

 #include <cstdio>

 #include <string>

 #include <vector>

 #include <bitset>

 #include <queue>

 #include <stack>

 #include <cmath>

 #include <ctime>

 #include <list>

 #include <set>

 #include <map>

 using namespace std;

 //using namespace __gnu_cxx;

 //define

 #define pii pair<int,int>

 #define mem(a,b) memset(a,b,sizeof(a))

 #define lson l,mid,rt<<1

 #define rson mid+1,r,rt<<1|1

 #define PI acos(-1.0)

 //typedef

 typedef long long LL;

 typedef unsigned long long ULL;

 //const

 const int N=;

 const int INF=0x3f3f3f3f;

 const int MOD=,STA=;

 const LL LNF=1LL<<;

 const double EPS=1e-;

 const double OO=1e15;

 const int dx[]={-,,,};

 const int dy[]={,,,-};

 const int day[]={,,,,,,,,,,,,};

 //Daily Use ...

 inline int sign(double x){return (x>EPS)-(x<-EPS);}

 template<class T> T gcd(T a,T b){return b?gcd(b,a%b):a;}

 template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}

 template<class T> inline T lcm(T a,T b,T d){return a/d*b;}

 template<class T> inline T Min(T a,T b){return a<b?a:b;}

 template<class T> inline T Max(T a,T b){return a>b?a:b;}

 template<class T> inline T Min(T a,T b,T c){return min(min(a, b),c);}

 template<class T> inline T Max(T a,T b,T c){return max(max(a, b),c);}

 template<class T> inline T Min(T a,T b,T c,T d){return min(min(a, b),min(c,d));}

 template<class T> inline T Max(T a,T b,T c,T d){return max(max(a, b),max(c,d));}

 //End

 int first[N*],next[*],vis[N*],S[N*];

 int n,m,mt,cnt;

 struct Edge{

     int u,v;

 }e[*];

 void adde(int a,int b)

 {

     e[mt].u=a,e[mt].v=b;

     next[mt]=first[a];first[a]=mt++;

 }

 int dfs(int u)

 {

     if(vis[u^])return ;

     if(vis[u])return ;

     int i;

     vis[u]=;

     S[cnt++]=u;

     for(i=first[u];i!=-;i=next[i]){

         if(!dfs(e[i].v))return ;

     }

     return ;

 }

 int Twosat()

 {

     int i,j;

     for(i=;i<n;i+=){

         if(vis[i] || vis[i^])continue;

         cnt=;

         if(!dfs(i)){

             while(cnt)vis[S[--cnt]]=;

             if(!dfs(i^))return ;

         }

     }

     return ;

 }

 int main()

 {

  //   freopen("in.txt","r",stdin);

     int i,j,a,b;

     while(~scanf("%d%d",&n,&m))

     {

         n<<=;

         mem(first,-);mt=;

         mem(vis,);

         for(i=;i<m;i++){

             scanf("%d%d",&a,&b);

             a--,b--;

             adde(a,b^);

             adde(b,a^);

         }

         if(Twosat()){

             for(i=;i<n;i+=){

                 printf("%d\n",(vis[i]?i:i^)+);

             }

         }

         else puts("NIE");

     }

     return ;

 }