View Compilation Error

0_0_26008669_5187.cpp: In function 'll dfs(ll, ll, ll)':
0_0_26008669_5187.cpp:15:35: error: 'z' was not declared in this scope
     if(x*y > num) tmp = (tmp+(x*y-z)%mod * dfs(x,y,num+1))%mod;
                                   ^