View Compilation Error

0_0_22723982_9797.cpp: In function 'int main()':
0_0_22723982_9797.cpp:45:37: error: 'z' was not declared in this scope
      k += q != 0 && rk[k][nex[to[k][z]]] != rk[k][nex[to[k][x[i][q - 1]]]];
                                     ^