Compile-Time Fixed Stack

#include <iostream>
#include <string>

// TODO: Define Class Template 'StaticStack'
// Template Parameters: typename T, int Capacity
template <typename T, int Capacity>
class StaticStack {
private:
    T buffer[Capacity]; // 0 , 1 , 2
    int top_index; // Points to the index of the next free slot OR current top

public:
    StaticStack() : top_index(-1) {}

    // TODO: Implement push(val) - Check for overflow
    void push(T val){
        if ( (top_index + 1) >= Capacity)
            std::cout << "Stack Overflow\n";
        else
        {
            buffer[top_index + 1] = val;
            top_index++;
        }
    }
    // TODO: Implement pop() - Check for underflow
    void pop()
    {
        if (top_index <= -1)
            std::cout << "Stack Underflow\n";
        else
            --top_index;
    }
    // TODO: Implement peek() - Return current top
    T peek()
    {
        if ( top_index <= -1) return T(0);
            return buffer[top_index];
    }
    // TODO: Implement isEmpty()
    bool isEmpty()
    {
        return top_index <= -1;
    }    
};

int main() {
    // Instantiate a stack of int with capacity 3
    StaticStack<int, 3> stack;

    int N;
    if (!(std::cin >> N)) return 0;

    for (int i = 0; i < N; ++i) {
        std::string cmd;
        std::cin >> cmd;

        if (cmd == "PUSH") {
            int val;
            std::cin >> val;
            stack.push(val);
        } else if (cmd == "POP") {
            stack.pop();
        } else if (cmd == "PEEK") {
            // Simple safety check for peek printing in main
            if (!stack.isEmpty()) {
                std::cout << "Top: " << stack.peek() << std::endl;
            } else {
                 std::cout << "Stack Empty" << std::endl;
            }
        } else if (cmd == "EMPTY") {
            std::cout << "Empty: " << (stack.isEmpty() ? "Yes" : "No") << std::endl;
        }
    }
    return 0;
}

Solving Approach