practica 5.6 consola

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace practica_5._6_console
{
class Program
{
static void Main(string[] args)
{
int c1, er;
c1 = 0;
er = 0;
do
{

Console.WriteLine(" \n Introduce Calificacion");
c1 = int.Parse(Console.ReadLine());
if (c1 < 0 || c1 > 100)
{
er = er + 1;

}
}
while (er < 5);
Console.ReadLine();
}
}
}