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

internal class Program {
    private static void Main() {
        do {
            Console.Write("x = ");
            var x = double.Parse(Console.ReadLine() ?? throw new InvalidOperationException());
            Console.Write("y = ");
            var y = double.Parse(Console.ReadLine() ?? throw new InvalidOperationException());

            Console.WriteLine($"A({x}, {y}) => {ContainsPoint(x, y)}");
        } while (true);

        Console.ReadKey();
    }

    private static string ContainsPoint(double x, double y) {
        var values = new List<double> {
            -(x - 70),
            x - y,
            y
        };

        if (values.Any(v => v < 0))
            return "Нет";
        return values.Any(v => Math.Abs(v) < 0.01) ? "На границе" : "Да"; // Math.Abs(v) < 0.01 сравнение с 0
    }
}