Given three natural numbers A, B, and C. Determine if a triangle with these sides can exist.
If the triangle exists, output the "YES" string; otherwise, output "NO".
A triangle is valid if the sum of its two sides is greater than the third side. If three sides are A, B, and C, then three conditions should be met.
1. A + B > C
2. A + C > B
3. B + C > A