#include <cstdio>
        #include <vector>
        using namespace std;
        vector <int> g[10001];
        int st[10001], dr[10001];
        bool cupleaza (int p, int &x)
        {
            int i;
            for (i=0; i<g[p].size(); i++)
            {
                if (dr[g[p][i]]==0)
                {
                    x=g[p][i];
                    return true;
                }
            }
            return false;
        }
        bool elibereaza (int x)
        {
            int p=dr[x], i;
            for (i=0; i<g[p].size(); i++)
            {
                if (st[g[p][i]]==0) return true;
                int y=g[p][i];
                if (elibereaza(y))
                {
                    st[p]=g[p][i];
                    dr[g[p][i]]=p;
                    return true;
                }
            }
            return false;
        }
        int main()
        {
            int n1, n2, m, i, j, x, y, nr=0;
            freopen("cuplaj.in","r",stdin);
            freopen("cuplaj.out","w",stdout);
            scanf("%d%d%d",&n1,&n2,&m);
            for (i=1; i<=m; i++)
            {
                scanf("%d%d",&x,&y);
                g[x].push_back(y);
                g[y].push_back(x);
            }
            for (i=1; i<=n1; i++)
            {
                if (cupleaza(i,x))
                {
                    nr++;
                    st[i]=x;
                    dr[x]=i;
                    continue;
                }
                for (j=0; j<g[i].size(); j++)
                {
                    if (elibereaza(g[i][j]))
                    {
                        nr++;
                        st[i]=g[i][j];
                        dr[g[i][j]]=i;
                        break;
                    }
                }
            }
            printf("%d\n",nr);
            for (i=1; i<=n1; i++)
            {
                if (st[i]!=0)
                {
                    printf("%d %d\n",st[i],dr[st[i]]);
                }
            }
            fclose(stdin);
            fclose(stdout);
            return 0;
        }