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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include<stdio.h>

void QSort(long x[ ], int left, int right)
{
    long i, j;
    long pivot;

    i = left;                      /* ソートする配列の一番小さい要素の添字 */
    j = right;                     /* ソートする配列の一番大きい要素の添字 */

    pivot = x[(left + right) / 2]; /* 基準値を配列の中央付近にとる */

    while (1) {                    /* 無限ループ */

        while (x[i] < pivot)       /* pivot より大きい値が */
            i++;                   /* 出るまで i を増加させる */

        while (pivot < x[j])       /* pivot より小さい値が */
            j--;                   /*  出るまで j を減少させる */
        if (i >= j)                /* i >= j なら */
            break;                 /* 無限ループから抜ける */

        Swap(x, i, j);             /* x[i] と x[j]を交換 */
        i++;                       /* 次のデータ */
        j--;
    }
    if (left < i - 1)              /* 基準値の左に 2 以上要素があれば */
        QSort(x, left, i - 1);     /* 左の配列を Q ソートする */
    if (j + 1 <  right)            /* 基準値の右に 2 以上要素があれば */
        QSort(x, j + 1, right);    /* 右の配列を Q ソートする */
}

  /* 配列の要素を交換する */
void Swap(long x[ ], int i, int j)
{
    long temp;

    temp = x[i];
    x[i] = x[j];
    x[j] = temp;
}

int main(){
  long n,i,j;
  long a[200000],sum[200001]={},xor[200001]={},sa[200010]={},cnt=0,left,right,c[2];
  scanf("%ld",&n);
  for(i=0;i<n;i++){
    scanf("%ld",&a[i]);
    sum[i+1]=sum[i]+a[i];
    xor[i+1]=xor[i]^a[i];
    sa[i+1]=sum[i+1]-xor[i+1];
  }
  QSort(sa, 1, n);
  sa[n+1]=sa[n]+1;
  left=1;
  for(i=1;i<=n+1;i++){
    for(j=i+1;j<=n+1;j++){
    c[0]=sum[j]-sum[i-1];
    c[1]=xor[j]^xor[i-1];
    if(c[0]!=c[1]||j==n+1){
      right=i;
      cnt+=(j-i-1);
      left=i;
break;
    }
}
  }
  printf("%ld\n",cnt+n);
}