View Compilation Error

0_0_13888437_1124.cpp:22:1: error: 'stact' does not name a type
 stact<int> q;
 ^
0_0_13888437_1124.cpp: In function 'void topsort()':
0_0_13888437_1124.cpp:51:7: error: 'q' was not declared in this scope
       q.push(i);
       ^
0_0_13888437_1124.cpp:52:11: error: 'q' was not declared in this scope
   while( !q.empty() ){
           ^