func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<int> A[7], B[100005];   int n, a[5005], f[5005][5005], ans;   int main() {     int i, j, u, v, w, p, q, r;     scanf( %d , &n);     for (i = 1; i <= n; i++) scanf( %d , &a[i]);     for (i = n; i >= 1; i--) {       A[a[i] % 7].push_back(i);       B[a[i]].push_back(i);     }     ans = 2;     for (i = 1; i <= n; i++) {       A[a[i] % 7].pop_back();       B[a[i]].pop_back();       u = A[a[i] % 7].size() ? A[a[i] % 7][A[a[i] % 7].size() - 1] : 0;       v = B[a[i] - 1].size() ? B[a[i] - 1][B[a[i] - 1].size() - 1] : 0;       w = B[a[i] + 1].size() ? B[a[i] + 1][B[a[i] + 1].size() - 1] : 0;       for (j = 0; j < i; j++) {         f[i][j] = max(f[i][j], f[j][0] + 1);         ans = max(ans, f[i][j]);         if (u) f[u][j] = max(f[u][j], f[i][j] + 1);         if (v) f[v][j] = max(f[v][j], f[i][j] + 1);         if (w) f[w][j] = max(f[w][j], f[i][j] + 1);         if (!j) continue;         p = A[a[j] % 7].size() ? A[a[j] % 7][A[a[j] % 7].size() - 1] : 0;         q = B[a[j] - 1].size() ? B[a[j] - 1][B[a[j] - 1].size() - 1] : 0;         r = B[a[j] + 1].size() ? B[a[j] + 1][B[a[j] + 1].size() - 1] : 0;         if (p) f[p][i] = max(f[p][i], f[i][j] + 1);         if (q) f[q][i] = max(f[q][i], f[i][j] + 1);         if (r) f[r][i] = max(f[r][i], f[i][j] + 1);       }     }     cout << ans;     return 0;   }   