#include <stdio.h>
#include <stdlib.h>

int *l, *c;
int **v;
int n, na, lung;
bool *viz;

void init();
void destroy();
bool dfs(int i);
void input();

int main() {
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);

    bool ok;
    int i, j;

    input();
    /*for (i = 0; i < n; ++i) {
        printf("Noduri %d: ", i);
        for (j = 0; j < l[i]; ++j)
            printf("%d ", v[i][j]);
        printf("\n");
    }*/

    for (i = 0; i < n; ++i)
        c[i] = -1;

    // cuplajul maximal
    for (i = 0; i < na; ++i)
        if (c[i] == -1)
            for (j = 0; j < l[i]; ++j)
                if (c[v[i][j]] == -1) {
                    c[i] = v[i][j];
                    c[v[i][j]] = i;
                    ++lung;
                    break;
                }

    /*for (i = 0; i < n; ++i)
        printf("%2d ", i);
    printf("\n");
    for (i = 0; i < n; ++i)
        printf("%2d ", c[i]);
    printf("\n");*/

    // cuplajul maxim
    ok = true;
    while (ok) {
        ok = false;
        for (i = 0; i < n; ++i)
            viz[i] = false;
        for (i = 0; i < na; ++i)
            if (!viz[i] && c[i] == -1)
                if (dfs(i)) {
                    ok = true;
                    ++lung;
                }
    }

    // afisare
    printf("%d\n", lung);
    for (i = 0; i < na; ++i)
        if (c[i] != -1)
            printf("%d %d\n", i + 1, c[i] - na + 1);

    destroy();
    return 0;
}

bool dfs(int i) {
    viz[i] = true;
    for (int j = 0; j < l[i]; ++j) {
        int k = v[i][j];
        if (viz[k] || c[i] == k)
            continue;
        if (c[k] == -1) {
            c[k] = i;
            c[i] = k;
            return true;
        }
        else {
            viz[k] = true;
            if (dfs(c[k])) {
                c[i] = k;
                c[k] = i;
                return true;
            }
            else
                continue;
        }
    } // for j
    return false;
}

void input() {
    int e, i, x, y;
    int a[100000], b[100000];
    scanf("%d %d %d", &na, &n, &e);
    n += na;
    init();
    for (i = 0; i < e; ++i) {
        scanf("%d %d", &x, &y);
        a[i] = x - 1;
        b[i] = na + y - 1;
        ++l[a[i]];
        ++l[b[i]];
        if (b[i] == 8)
            i = i;
    }
    for (i = 0; i < n; ++i) {
        v[i] = (int*)calloc(l[i], sizeof(int));
        l[i] = 0;
    }
    for (i = 0; i < e; ++i) {
        v[a[i]][l[a[i]]++] = b[i];
        v[b[i]][l[b[i]]++] = a[i];
        if (b[i] == 8)
            ;
    }
}

void init() {
    l = (int*)calloc(n, sizeof(int));
    c = (int*)calloc(n, sizeof(int));
    v = (int**)calloc(n, sizeof(int*));
    viz = (bool*)calloc(n, sizeof(bool));
}

void destroy() {
    free(l);
    free(c);
    for (int i = 0; i < n; ++i)
        free(v[i]);
    free(v);
    free(viz);
}