#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, U b) {
  if (a < b) a = b;
}
template <class T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <class T>
inline void println(T first) {
  print(first);
  putchar('\n');
}
template <class T>
inline void printsp(T first) {
  print(first);
  putchar(' ');
}
template <class T1, class T2>
inline void print(T1 x1, T2 x2) {
  printsp(x1), println(x2);
}
template <class T1, class T2, class T3>
inline void print(T1 x1, T2 x2, T3 x3) {
  printsp(x1), printsp(x2), println(x3);
}
template <class T1, class T2, class T3, class T4>
inline void print(T1 x1, T2 x2, T3 x3, T4 x4) {
  printsp(x1), printsp(x2), printsp(x3), println(x4);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a % m)
    if (b & 1) ans = 1LL * ans * a % m;
  return ans;
}
int val[10][10];
int a[2022][2022];
int q[2022];
int mx[2022][2022][10];
int now[10];
int main() {
  int n, m, k, s;
  cin >> n >> m >> k >> s;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) gn(a[i][j]);
  }
  for (int i = 0; i < s; i++) gn(q[i]);
  for (int i = 0; i < 2022; i++)
    for (int j = 0; j < 2022; j++)
      for (int p = 0; p < 10; p++) mx[i][j][p] = -0x3f3f3f3f;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      smax(mx[i][j][a[i][j]], 0);
      for (int p = 1; p <= k; p++) {
        smax(mx[i][j][p], max(mx[i][j - 1][p], mx[i - 1][j][p]) + 1);
        smax(val[a[i][j]][p], mx[i][j][p]);
        smax(val[p][a[i][j]], mx[i][j][p]);
      }
    }
  }
  for (int i = 0; i < 2022; i++)
    for (int j = 0; j < 2022; j++)
      for (int p = 0; p < 10; p++) mx[i][j][p] = -0x3f3f3f3f;
  for (int i = n; i >= 1; i--) {
    for (int j = 1; j <= m; j++) {
      smax(mx[i][j][a[i][j]], 0);
      for (int p = 1; p <= k; p++) {
        smax(mx[i][j][p], max(mx[i][j - 1][p], mx[i + 1][j][p]) + 1);
        smax(val[a[i][j]][p], mx[i][j][p]);
        smax(val[p][a[i][j]], mx[i][j][p]);
      }
    }
  }
  int ans = 0;
  for (int i = 1; i < s; i++) smax(ans, val[q[i - 1]][q[i]]);
  cout << ans << endl;
  return 0;
}
