#include<cstdio>#include<cstdlib>#include<cstring>#include<iostream>#include<algorithm>#include<queue>#include<set>using namespace std;int n,m,k;set<int>s;int f[200000],g[200000];int sum[200000],tot,sedge;struct point {    int to,next;}e[10000000];void add(int x,int y){    e[++tot].to=y;    e[tot].next=g[x];    g[x]=tot;}int main(){    freopen("graph.in","r",stdin);    freopen("graph.out","w",stdout);    scanf("%d%d%d",&n,&m,&k);    for(int i=1;i<=m;i++)    {        int x,y;        scanf("%d%d",&x,&y);        add(x,y);        sum[y]++;    }    for(int i=1;i<=n;i++)    {        if(sum[i]==0)        s.insert(i);    }//cout<<"!!!!!!"<<endl;    int sk=k;    for(int p=1;p<=n;p++)    {        int flag=1;        set<int>::iterator itlast=s.end();itlast--;//cout<<"!!!!!!"<<endl;        set<int>::iterator itar;        //cout<<*itlast<<endl;        for(set<int>::iterator it=s.begin();it!=itlast;it++)        {//cout<<"!!!!!!"<<endl;            //cout<<*it<<endl;            if(f[*it])            {                set<int>::iterator tmp=it;                tmp++;                f[*it]=*tmp;                add(*tmp,*it);                sum[*it]++;                continue;            }            if(f[*it]==0&&sk>0)            {                set<int>::iterator tmp=it;                tmp++;                f[*it]=*tmp;                //cout<<*tmp<<" "<<*it<<endl;                add(*tmp,*it);                sum[*it]++;//cout<<"!!!!!!"<<endl;                sk--;                continue;            }            printf("%d ",*it);            itar=it;            flag=0;            break;        }        if(flag)        {            set<int>::iterator itlast=s.end();itlast--;            printf("%d ",*itlast);            int x=*itlast;            s.erase(s.begin(),s.find(x));            s.erase(x);            for(int temp=g[x];temp;temp=e[temp].next)            {                sum[e[temp].to]--;                if(sum[e[temp].to]==0)                s.insert(e[temp].to);            }        }        else        {            int x=*itar;            s.erase(s.begin(),s.find(x));            s.erase(x);            for(int temp=g[x];temp;temp=e[temp].next)            {                sum[e[temp].to]--;                if(sum[e[temp].to]==0)                s.insert(e[temp].to);            }        }    }    int ans=0;    for(int i=1;i<=n;i++)    {        if(f[i])ans++;    }    cout<<endl<<ans<<endl;    for(int i=1;i<=n;i++)    if(f[i])printf("%d %d\n",f[i],i);    return 0;}