View Compilation Error

0_0_36619173_20454.cpp: In function 'int main()':
0_0_36619173_20454.cpp:28:38: error: 't' was not declared in this scope
    printf("Case %d is not a tree.\n",t++);
                                      ^
0_0_36619173_20454.cpp:35:39: error: 't' was not declared in this scope
     printf("Case %d is not a tree.\n",t++);
                                       ^
0_0_36619173_20454.cpp:37:35: error: 't' was not declared in this scope
     printf("Case %d is a tree.\n",t++);
                                   ^