# include<iostream>

# include<cstdio>

# include<cstring>

# include<algorithm>

using namespace std;

# define REP(i,s,n) for(int i=s;i<n;++i)

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

# define CLL(a,b,n) fill(a,a+n,b)

const int N=1005;

struct Edge

{

    int to,nxt;

};

Edge e[N*N];

int link[N],visx[N],visy[N],vis[2*N],mark[N];

int cnt,n,m,head[N];

void add(int u,int v)

{

    e[cnt].to=v;

    e[cnt].nxt=head[u];

    head[u]=cnt++;

}

void dfs1(int x)

{

    visx[x]=1;

    for(int i=head[x];i!=-1;i=e[i].nxt){

        int y=e[i].to;

        if(visy[y]) continue;

        visy[y]=1;

        dfs1(link[y]);

    }

}

bool dfs(int x)

{

    for(int i=head[x];i!=-1;i=e[i].nxt){

        int y=e[i].to;

        if(vis[y]) continue;

        vis[y]=1;

        if(link[y]==-1||dfs(link[y])){

            link[y]=x;

            return true;

        }

    }

    return false;

}

int match()

{

    int res=0;

    REP(i,1,n+1){

        CL(vis,0);

        if(dfs(i)) ++res;

    }

    return res;

}

int main()

{

    int a,b,k;

    while(scanf("%d%d%d",&n,&m,&k)&&(n+m+k))

    {

        cnt=0;

        CL(head,-1);

        CL(link,-1);

        CL(mark,0);

        CL(visx,0);

        CL(visy,0);

        while(k--)

        {

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

            add(a,b);

        }

        int ans=match();

        REP(i,1,m+1) if(link[i]!=-1) mark[link[i]]=1;

        REP(i,1,n+1) if(!mark[i]) dfs1(i);

        printf("%d",ans);

        REP(i,1,n+1) if(!visx[i]) printf(" r%d",i);

        REP(i,1,m+1) if(visy[i]) printf(" c%d",i);

        printf("\n");

    }

    return 0;

}