#include <iostream>

 #include <cstdio>

 #include <cstdlib>

 #include <cstring>

 using namespace std;

 const int maxn =  + ;

 int c[maxn], ans, maxx;

 int main()

 {

     int n, x;

     while (scanf("%d%d%d", &n, &x, &x) != EOF)

     {

         ans = ;

         for (int i = ; i < n; i++)

             scanf("%d", &c[i]);

         for (int i = ; i < n; i++)

         {

             int k, j;

             if (c[i] == c[i-] && c[i] == x)

             {

                 int l = i-;

                 int r = i+;

                 int s = ;

                 while ()

                 {

                     int k1 = , k2 = ;

                     for (j = l; j >= ; j--)

                     {

                         if (c[j] != c[l])

                             break;

                         k1++;

                     }

                     for (k = r; k < n; k++)

                     {

                         if (c[k] != c[r])

                             break;

                         k2++;

                     }

                     if (k1 + k2 >=  && c[l] == c[r])

                     {

                         l = j;

                         r = k;

                         s += k1+k2;

                     }

                     else

                     {

                         ans = max(ans, s);

                         break;

                     }

                 }

             }

         }

         printf("%d\n", ans);

     }

     return ;

 }