Simple stack implementation in c++

stack.cpp

#include <iostream>
// #include <stdexcept>
using namespace std;

template<typename T>
class Stack {
    typedef struct Node {
        T data;
        struct Node* next;
    } Node;
    Node* top;

public:
    T peek() {
        if(top == nullptr)
            throw runtime_error("Peek empty stack");
        return top->data;
    }

    void push(T data) {
        top = new Node{data, top};
    }

    void pop() {
        if(!top)
            throw runtime_error("Pop empty stack");
        Node* n = top;
        top = top->next;
        delete n;
    }
};

int main() {
    Stack<int> s;
    string cmd;
    int arg;
    while(cin >> cmd) {
        if(cmd == "push") {
            cin >> arg; s.push(arg);
        } else if(cmd == "pop") {
            s.pop();
        } else if(cmd == "peek") {
            cout << s.peek() << endl;
        }
    }
}