func_code_string: #include <bits/stdc++.h>   using namespace std;   int lsone(int n) { return (n & -n); }   void mult(long long int a[25][25], long long int b[25][25],             long long int c[25][25], int m, int n, int p) {     for (int i = 1; i <= m; i++) {       for (int j = 1; j <= p; j++) {         c[i][j] = 0;         for (int k = 1; k <= n; k++) {           c[i][j] += (a[i][k] * b[k][j]) % 1000000007;           c[i][j] %= 1000000007;         }       }     }   }   void mat_pow(long long int a[25][25], long long int c[25][25], int n,                long long int p) {     if (p == 0) {       for (int i = 1; i <= n; i++) c[i][i] = 1;     } else if (p == 1) {       for (int i = 1; i <= n; i++) {         for (int j = 1; j <= n; j++) c[i][j] = a[i][j];       }     } else {       long long int d[25][25];       mat_pow(a, d, n, p / 2);       if (p % 2) {         long long int e[25][25];         mult(d, d, e, n, n, n);         mult(e, a, c, n, n, n);       } else {         mult(d, d, c, n, n, n);       }     }   }   long long int pow1(long long int a, long long int b) {     if (b == 0)       return 1ll;     else if (b == 1)       return a;     else {       long long int x = pow1(a, b / 2);       x *= x;       x %= 1000000007;       if (b % 2) {         x *= a;         x %= 1000000007;       }       return x;     }   }   int n, m, k, s, temp, dist[10][10], a[2010][2010], mdist[10], q[101000];   vector<vector<int> > mat(21000);   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     ;     cin >> n >> m >> k >> s;     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= m; j++) {         cin >> temp;         a[i][j] = temp;         mat[(temp - 1) * m + j].push_back(i);       }     }     for (int i = 1; i <= k; i++) {       for (int j = 1; j <= m; j++)         sort(mat[(i - 1) * m + j].begin(), mat[(i - 1) * m + j].end());     }     for (int i = 1; i <= n; i++) {       memset(mdist, -1, sizeof(mdist));       for (int j = 1; j <= m; j++) {         for (int x = 1; x <= k; x++) {           if (mdist[x] != -1) mdist[x]++;           int minim = n, maxim = 0;           if (mat[(x - 1) * m + j].size() > 0) {             minim = mat[(x - 1) * m + j][0];             maxim = mat[(x - 1) * m + j][mat[(x - 1) * m + j].size() - 1];           }           int dist1 = i - minim, dist2 = maxim - i;           mdist[x] = max(mdist[x], max(dist1, dist2));           dist[a[i][j]][x] = max(dist[a[i][j]][x], mdist[x]);           dist[x][a[i][j]] = dist[a[i][j]][x];         }       }     }     for (int i = 1; i <= n; i++) {       memset(mdist, -1, sizeof(mdist));       for (int j = m; j >= 1; j--) {         for (int x = 1; x <= k; x++) {           if (mdist[x] != -1) mdist[x]++;           int minim = n, maxim = 0;           if (mat[(x - 1) * m + j].size() > 0) {             minim = mat[(x - 1) * m + j][0];             maxim = mat[(x - 1) * m + j][mat[(x - 1) * m + j].size() - 1];           }           int dist1 = i - minim, dist2 = maxim - i;           mdist[x] = max(mdist[x], max(dist1, dist2));           dist[a[i][j]][x] = max(dist[a[i][j]][x], mdist[x]);           dist[x][a[i][j]] = dist[a[i][j]][x];         }       }     }     int ans = 0;     for (int i = 1; i <= s; i++) {       cin >> q[i];     }     for (int i = 2; i <= s; i++) {       ans = max(ans, dist[q[i - 1]][q[i]]);     }     cout << ans <<   n ;     return 0;   }   