View Compilation Error

0_0_21800306_9826.cpp: In function 'long long int dfs(int, int, int, bool)':
0_0_21800306_9826.cpp:31:27: error: 'zt' was not declared in this scope
  if (!limit&&dp[pos][pre][zt] != -1) return dp[pos][pre][sta];
                           ^