Unnamed Template Misparsing

/*Write a class template that uses a vector to implement a stack data structure.*/

/*Modify your solution to the previous exercise so that the type of the container
 used to implement the stack is a template template parameter.*/
#include <vector>
#include <iostream>
#include <stdexcept>

using namespace std;

template<class T, template<class U, class = allocator<U> > class Cont>
class Stack {
  Cont<T> stack;
public:
  void push(const T& t);
  void pop();
  const T& top();
  bool empty() { return stack.empty(); }
};

template<class T, template<class U, class = allocator<U> > class Cont>
void Stack<T,Cont>::push(const T& t) {
 stack.push_back(t);
}

template<class T, template<class U, class = allocator<U> > class Cont>
void Stack<T,Cont>::pop() {
  if (stack.empty() ) throw runtime_error("Stack empty");
  stack.erase(stack.end()-1, stack.end());
}

template<class T, template<class U, class = allocator<U> > class Cont>
const T& Stack<T,Cont>::top() {
  if ( stack.empty() ) throw runtime_error("Stack empty");
  return *(stack.end()-1);
}

int main(int argc, char**argv)
{
 Stack<int,vector> st;
 st. push(1);
 st.push(2);
 st. push(3);
 try {
 while (!st.empty()) {
   cout << st.top() << " ";
   st.pop();
 }
 } catch (std::runtime_error& e) {
  cout << e.what() << endl;
 }
 cout << endl;
 return 0;
}