line = readlines.map(&:chomp)

N = line[0].to_i
S = line[1]

w_cum = []
r_cum = []

wcum = 0
for i in 1..N do
  if S[i-1] == "W" then
    wcum += 1
  end
  w_cum[i-1] = wcum
  r_cum[i-1] = i - w_cum[i-1]
end
  
r_to_w = []
w_to_r = []
for i in 1..(N+1) do
  if i == 1 then
    r_to_w[i-1] = r_cum[N-1]
    w_to_r[i-1] = 0
  elsif i <= N then
    r_to_w[i-1] = r_cum[N-1] - r_cum[i-2]
    w_to_r[i-1] = w_cum[i-2]
  else
    r_to_w[i-1] = 0
    w_to_r[i-1] = w_cum[N-1]
  end
end
    
def max(x,y)
  if x > y then
    return x
  else
    return y
  end
end
  
num_alter = []
for i in 1..(N+1) do
  num_alter[i-1] = max(r_to_w[i-1],w_to_r[i-1])
end
  
ans = 10 ** 10
for i in 1..(N+1) do
  if num_alter[i-1] < ans then
    ans = num_alter[i-1]
  end
end
puts ans