import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            int length = in.nextInt();
            String a = in.next();
            String b = in.next();
            String[] strings = new String[length];
            int j = 0; 
            while(in.hasNext()){
                strings[j] = in.next();
                j++;
            }
             in.nextLine(); // 消耗掉 nextInt() 后的换行符
            int prev1 = -1;
            int prev2 = -1;
            int ret = Integer.MAX_VALUE;
            for (int i = 0; i < length; i++) {
                if (strings[i].equals(a)) {
                    prev1 = i;
                    if (prev2 != -1) {
                       ret = Math.min(ret,i-prev2);
                    }
                }
                if (strings[i].equals(b)) {
                    prev2 = i;
                    if (prev1 != -1) {
                       ret = Math.min(ret,i-prev1);
                    }
                }
            }

            System.out.println(ret == Integer.MAX_VALUE?-1:ret);
        }
    }
}