#include <cstdio>#include <iostream>#include <queue>#include <vector>#include <algorithm>using namespace std;const int MAX= 100100;vector<int> num[MAX];queue<int> que[2];int n1, n2, d;int dat[MAX], bak[MAX];int line(int k){ return k>n1?1:0;}int bfs( int k ){ int i; for ( i = 0 ; i < 2 ; i++ ) { while ( !que[i].empty() ) que[i].pop(); } for ( i = 1 ; i <= n1+n2 ; i++ ) { if ( !dat[i] ) que[line(i)].push(i); } int count = 1 ; while ( !que[0].empty() || !que[1].empty() ) { while(!que[k].empty()) { int t= que[k].front(); que[k].pop(); for ( i = 0 ; i < num[t].size() ; i++ ) { if ( !(--dat[num[t][i]]) ) { que[line(num[t][i])].push(num[t][i]); } } } k^=1; count++; } return count;}int main(){ while ( scanf("%d%d%d", &n1, &n2, &d) , n1 || n2 || d ) { int i, x, y; for ( i = 1 ; i <= n1+n2 ; i++ ) { num[i].clear(); bak[i]= 0; } for ( i = 0 ; i < d ; i++ ) { scanf("%d%d", &x, &y); num[y].push_back(x); bak[x]++; } for ( i = 1 ; i <= n1+n2 ; i++ ) dat[i]=bak[i]; x=bfs(0); for ( i = 1 ; i <= n1+n2 ; i++ ) dat[i]=bak[i]; y=bfs(1); printf("%dn", x<y?x:y); } return 0;}
