Brackets format checker

using System;
using System.Collections.Generic;
using System.Numerics;

namespace SoftuniExercisesWithVariables
{
    class Program
    {
        static bool isWellFormatted(string line)
        {
            Stack<char> lastOpen = new Stack<char>();
            foreach (var c in line)
            {
                switch (c)
                {
                    case ')':
                        if (lastOpen.Count == 0 || lastOpen.Pop() != '(') return false;
                        break;
                    case ']':
                        if (lastOpen.Count == 0 || lastOpen.Pop() != '[') return false;
                        break;
                    case '}':
                        if (lastOpen.Count == 0 || lastOpen.Pop() != '{') return false;
                        break;
                    case '(': lastOpen.Push(c); break;
                    case '[': lastOpen.Push(c); break;
                    case '{': lastOpen.Push(c); break;
                }
            }
            if (lastOpen.Count == 0) return true;
            else return false;
        }

        static void Main(string[] args)
        {
            Console.WriteLine("Enter your statement here: ");
            string statement = Console.ReadLine();
            bool check = isWellFormatted(statement);
            if(check == true)
            {
                Console.WriteLine("Your statement is well formatted.");
            }
            else
            {
                Console.WriteLine("Your statement is not formatted right.");
            }
        }
    }
}