二分图匹配（匈牙利算法）

/*
    二分图匹配
    匈牙利
    by sbn
*/
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
bool map[1001][1001];
int n1,n2,m;
int flag[1001],vis[1001];
bool dfs(int x){

    for (int i1=1;i1<=n2;i1++){
        if (map[x][i1]&&!vis[i1]){
            vis[i1]=1;
            if (flag[i1]==0||dfs(flag[i1])){
                flag[i1]=x;
                return true;
            }
        }
    }
    return false;
}
int main(){
    cin>>n1>>n2>>m;
    for (int i=1;i<=m;i++)
    {
        int a,b;
        cin>>a>>b;
        if (a<=n1&&b<=n2)
        map[a][b]=1;
    }
    int ans=0;
    for (int i=1;i<=n1;i++)
        {
        memset(vis,0,sizeof(vis));
        if (dfs(i)) ans++;
        }
    cout<<ans<<endl;
}