[Init] Solved solutions

cs/691A.cs

@@ -0,0 +1,21 @@
+using System;
+
+namespace problem_691A
+{
+	class problem_691A
+	{
+		public static void Main(string[] args)
+		{
+			Console.ReadLine();
+			string s = Console.ReadLine();
+			if ((s.IndexOf('0') == s.LastIndexOf('0') && s.Contains("0") && s.Contains("1")) || s == "1")
+			{
+				Console.Write("YES");
+			}
+			else
+			{
+				Console.Write("NO");
+			}
+		}
+	}
+}