#include <bits/stdc++.h>
using namespace std;
class InParser {
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch() {
		++sp;
		if (sp == 4096) {
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume) {
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n) {
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n) {
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
};
ofstream fout("cuplaj.out");
int t,i,j,n,m,e,x,y,l[10005],r[10005],cnt;
bool u[10005];
vector<int> g[10005];
bool pairup(int nod)
{
    if(u[nod])return 0;
    u[nod]=1;
    for(auto it:g[nod])
        if(!r[it])
        {
            l[nod]=it;
            r[it]=nod;
            return 1;
        }
    for(auto it:g[nod])
        if(pairup(r[it]))
        {
            l[nod]=it;
            r[it]=nod;
            return 1;
        }
    return 0;
}
signed main()
{
    InParser fin("cuplaj.in");
    //fin>>t;
    t=1;
    while(t--)
    {
        fin>>n>>m>>e;
        cnt=0;
        for(i=1;i<=n;i++)
        {
            g[i].clear();
            u[i]=0;
            l[i]=0;
        }
        for(i=1;i<=m;i++)
            r[i]=0;
        for(i=1;i<=e;i++)
        {
            fin>>x>>y;
            g[x].push_back(y);
        }
        bool ok=1;
        while(ok)
        {
            ok=0;
            for(i=1;i<=n;i++)
                u[i]=0;
            for(i=1;i<=n;i++)
                if(!l[i])
                    ok|=pairup(i);
        }
        for(i=1;i<=n;i++)
            if(l[i])
                cnt++;
        fout<<cnt<<'\n';
        for(i=1;i<=n;i++)
            if(l[i])
                fout<<i<<' '<<l[i]<<'\n';
    }
    return 0;
}