|There are N cities in a country, numbered 0 to N-1. Each pair of cities is connected by a bidirectional road.
John plans to travel through the country using the following rules:
Return the number of paths he can choose, modulo 1,000,000,007.
|-||roads will contain between 2 and 50 elements, inclusive.|
|-||Each element of roads will contain n characters, where n is the number of elements in roads.|
|-||Each character in roads will be 'Y' or 'N'.|
|-||The i-th character in the i-th element of roads will be 'N'.|
|-||The j-th character in the i-th element of roads and the i-th character in the j-th element of roads will be equal.|