/in/foo.cc:6:8: error: 'unit' was not declared in this scope
  stack<unit> a;
        ^~~~
/in/foo.cc:6:12: error: template argument 1 is invalid
  stack<unit> a;
            ^
/in/foo.cc:6:12: error: template argument 2 is invalid
/in/foo.cc: In function 'int main()':
/in/foo.cc:28:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<t.length();i++){
                 ~^~~~~~~~~~~
/in/foo.cc:34:15: error: request for member 'push' in 'a', which is of non-class type 'int'
             a.push(t);
               ^~~~
/in/foo.cc:37:26: error: request for member 'top' in 'a', which is of non-class type 'int'
             unit right=a.top();
                          ^~~
/in/foo.cc:38:15: error: request for member 'pop' in 'a', which is of non-class type 'int'
             a.pop();
               ^~~
/in/foo.cc:39:26: error: request for member 'top' in 'a', which is of non-class type 'int'
             unit  left=a.top();
                          ^~~
/in/foo.cc:40:15: error: request for member 'pop' in 'a', which is of non-class type 'int'
             a.pop();
               ^~~
/in/foo.cc:46:19: error: request for member 'push' in 'a', which is of non-class type 'int'
                 a.push(tt);
                   ^~~~
/in/foo.cc:54:19: error: request for member 'push' in 'a', which is of non-class type 'int'
                 a.push(tt);
                   ^~~~
/in/foo.cc:63:19: error: request for member 'push' in 'a', which is of non-class type 'int'
                 a.push(tt);
                   ^~~~
/in/foo.cc:72:19: error: request for member 'push' in 'a', which is of non-class type 'int'
                 a.push(tt);
                   ^~~~
/in/foo.cc:76:13: error: request for member 'top' in 'a', which is of non-class type 'int'
     cout<<a.top().inf;
             ^~~