#include < iostream >
using   namespace  std;

struct  arr{
     int  x,y,c;
}a[ 25000 ];
int  N,k,m;
int  p[ 10010 ];
int  Find( int  x){
     if (x != p[x]) p[x] = Find(p[x]);
     return  p[x];
}
int  main()
{
    scanf( " %d%d%d " , & N, & k, & m);
     for ( int  i = 1 ;i <= k; ++ i){
        scanf( " %d%d " , & a[i].x, & a[i].y);
        a[i].c = 0 ;
    }
     for ( int  i = 1 ;i <= m; ++ i){
        scanf( " %d%d " , & a[i + k].x, & a[i + k].y);
        a[i + k].c = 1 ;
    }
     for ( int  i = 1 ;i <= N; ++ i)
        p[i] = i;
     int  l = 0 ,ans = 0 ;
     for ( int  i = 1 ;i <= k + m; ++ i){
         int  x = Find(a[i].x),y = Find(a[i].y);
         if (x != y){
            ans += a[i].c;
            l ++ ;
             if (l == N - 1 )  break ;
            p[x] = y;
        }
    }
    printf( " %d\n " ,ans);
     return   0 ;
}