import java.io.*;
import java.util.StringTokenizer;
public class aaa{
  public static void main(String argumendid[])
  throws IOException{
    BufferedReader klaviatuur=new BufferedReader(
      new InputStreamReader(System.in)
    );
    System.out.println("Palun failinimi:");
    String failinimi=klaviatuur.readLine();
    System.out.println("Palun täht");
    String taht=klaviatuur.readLine();
    BufferedReader sisse=new BufferedReader(
      new FileReader(failinimi)
    );
    String rida=sisse.readLine();
    char c = taht.charAt(0);
    int max = -1;
    String maxsona = null;
    while(rida!=null){
      StringTokenizer st=new StringTokenizer(rida, " ");
      while(st.hasMoreTokens()){
        String sona=st.nextToken();	
	int x = 0;
	for(int i=0; i < sona.length();i++) {
		if (sona.charAt(i) == c) {
			x++;
		}
	}
	if (max < x) {
		max = x;
		maxsona = sona;
	}
      }
      rida=sisse.readLine();
    }
    System.out.println(maxsona);
  }
}