using System;
namespace ConsoleApplication_C_Sharp
{
class Program
{
static void Main(string[] args)
{
string s = "c# java c++";
if (IsLower(s))
Console.WriteLine("yes");
else
Console.WriteLine("no");
}
public static bool IsLower(string s)
{
for (int i = 0; i < s.Length; i++)
{
if (char.IsUpper(s[i]))
{
return false;
}
}
return true;
}
}
}
/*
run:
yes
*/