Problem:
Score : 300 points

Problem Statement

There are N people standing in a row from west to east.
Each person is facing east or west.
The directions of the people is given as a string S of length N.
The i-th person from the west is facing east if S_i = E, and west if S_i = W.

You will appoint one of the N people as the leader, then command the rest of them to face in the direction of the leader.
Here, we do not care which direction the leader is facing.

The people in the row hate to change their directions, so you would like to select the leader so that the number of people who have to change their directions is minimized.
Find the minimum number of people who have to change their directions.

Constraints

2 \leq N \leq 3 \times 10^5

|S| = N

S_i is E or W.

Input

Input is given from Standard Input in the following format:

N
S

Output

Print the minimum number of people who have to change their directions.

Sample Input 1

5
WEEWW

Sample Output 1

1

Assume that we appoint the third person from the west as the leader.
Then, the first person from the west needs to face east and has to turn around.
The other people do not need to change their directions, so the number of people who have to change their directions is 1 in this case.
It is not possible to have 0 people who have to change their directions, so the answer is 1.

Sample Input 2

12
WEWEWEEEWWWE

Sample Output 2

4

Sample Input 3

8
WWWWWEEE

Sample Output 3

3

Solution in C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

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

namespace AtCoder
{
    class Program
    {
        static int n;
        static string s;

        static void Main(string[] args)
        {
            //[summary]C - Attention
            n = int.Parse(Console.ReadLine().TrimEnd());
            s = Console.ReadLine().TrimEnd();

            int min = GetMinimumTurnedPeople();
            Console.WriteLine(min);
        }

        static int GetMinimumTurnedPeople()
        {
            int min = n;

            for(int i = 0; i < n; i++)
            {
                int count = CountTurnedPeople(i);

                if (count == 0)
                {
                    return 0;
                }
                else if (count < min)
                {
                    min = count;
                }
            }

            return min;
        }

        static int CountTurnedPeople(int index)
        {
            int count = 0;

            for(int i = 0; i < n; i++)
            {
                if (i < index && s[i] == 'W')
                {
                    count++;
                }
                else if (i > index && s[i] == 'E')
                {
                    count++;
                }
            }

            return count;
        }

        static IEnumerable<List<T>> ReadLines<T>(int count = 0, char separator = ' ')
        {
            //[summary]コンソールの値を読み込んで、List<T>のコレクションを返却

            //読み込む行数が未指定のときは、1行目の値を"count"とみなす
            if (count == 0)
            {
                string line = Console.ReadLine().TrimEnd();
                count = int.Parse(line);
            }

            for (int i = 0; i < count; i++)
            {
                //コンソールを1行読み込み
                string line = Console.ReadLine().TrimEnd();

                //char型のときは1文字ずつに分割
                if (typeof(T) == typeof(char))
                {
                    var list = line.ToCharArray().ToList();
                    yield return (List<T>)(object)list;
                }
                else
                {
                    //読み込んだ値を"separator"で区切る
                    var list = line.Split(separator).ToList();

                    //int型のときは数値に変換
                    if (typeof(T) == typeof(int))
                    {
                        var numbers = list.ConvertAll(int.Parse);
                        yield return (List<T>)(object)numbers;
                    }
                    else
                    {
                        yield return (List<T>)(object)list;
                    }
                }
            }
        }
    }
}