#include <iostream>
#include <cstring>

using namespace std;

void solve(int n,int q);

int main(void){
  int n,q;
  while(true){
    cin >> n;
    cin >> q;
    if(n==0 && q==0) break;
    solve(n,q);
    
  }
}

void solve(int n,int q){
  int date[100];
  int maxday;
  int maxman;
  int m,d;
  
  maxday = 1;
  maxman = 0;
  memset(date,0,sizeof(date));
  
  for(int n_count=0; n_count<n; n_count++){
    cin >> m;
    for(int i=0;i<m;i++){
      cin >> d;
      date[d]++;
      if(date[d]> maxman){
	maxman = date[d];
	maxday = d;
      }else if(date[d] == maxman && d < maxday){
	maxday = d;
      }
    }
  }
  if(maxman < q){
    cout << 0 << endl;
  }else{
    cout << maxday << endl;
  }
}