#include <bits/stdc++.h>
using namespace std;
template <typename T>
T in() {
  char ch;
  T n = 0;
  bool ng = false;
  while (1) {
    ch = getchar();
    if (ch == '-') {
      ng = true;
      ch = getchar();
      break;
    }
    if (ch >= '0' && ch <= '9') break;
  }
  while (1) {
    n = n * 10 + (ch - '0');
    ch = getchar();
    if (ch < '0' || ch > '9') break;
  }
  return (ng ? -n : n);
}
template <typename T>
inline T POW(T B, T P) {
  if (P == 0) return 1;
  if (P & 1)
    return B * POW(B, P - 1);
  else
    return (POW(B, P / 2) * POW(B, P / 2));
}
template <typename T>
inline T Gcd(T a, T b) {
  if (a < 0) return Gcd(-a, b);
  if (b < 0) return Gcd(a, -b);
  return (b == 0) ? a : Gcd(b, a % b);
}
template <typename T>
inline T Lcm(T a, T b) {
  if (a < 0) return Lcm(-a, b);
  if (b < 0) return Lcm(a, -b);
  return a * (b / Gcd(a, b));
}
long long Bigmod(long long base, long long power, long long MOD) {
  long long ret = 1;
  while (power) {
    if (power & 1) ret = (ret * base) % MOD;
    base = (base * base) % MOD;
    power >>= 1;
  }
  return ret;
}
bool isVowel(char ch) {
  ch = toupper(ch);
  if (ch == 'A' || ch == 'U' || ch == 'I' || ch == 'O' || ch == 'E')
    return true;
  return false;
}
template <typename T>
long long int isLeft(T a, T b, T c) {
  return (a.x - b.x) * (b.y - c.y) - (b.x - c.x) * (a.y - b.y);
}
long long ModInverse(long long number, long long MOD) {
  return Bigmod(number, MOD - 2, MOD);
}
bool isConst(char ch) {
  if (isalpha(ch) && !isVowel(ch)) return true;
  return false;
}
int toInt(string s) {
  int sm;
  stringstream second(s);
  second >> sm;
  return sm;
}
int a[3][77];
int Ln[3];
int n;
int dp[77][77][77][2];
int lol(int v, int k, int x, int f) {
  if ((v + k + x) == n) return 0;
  int &res = dp[v][k][x][f];
  if (res != -1) return res;
  res = 20000;
  int np = v + k + x + 1;
  if (v < Ln[1]) {
    int tp = 0;
    int ps = a[1][v];
    for (int i = x; i < Ln[0]; i++) {
      if (a[0][i] < ps)
        tp++;
      else
        break;
    }
    for (int i = k; i < Ln[2]; i++) {
      if (a[2][i] < ps)
        tp++;
      else
        break;
    }
    res = min(res, tp + lol(v + 1, k, x, 1));
  }
  if (!f) {
    if (k < Ln[2]) {
      int tp = 0;
      int ps = a[2][k];
      for (int i = x; i < Ln[0]; i++) {
        if (a[0][i] < ps)
          tp++;
        else
          break;
      }
      for (int i = v; i < Ln[1]; i++) {
        if (a[1][i] < ps)
          tp++;
        else
          break;
      }
      res = min(res, tp + lol(v, k + 1, x, 0));
    }
  }
  if (x < Ln[0]) {
    int tp = 0;
    int ps = a[0][x];
    for (int i = v; i < Ln[1]; i++) {
      if (a[1][i] < ps)
        tp++;
      else
        break;
    }
    for (int i = k; i < Ln[2]; i++) {
      if (a[2][i] < ps)
        tp++;
      else
        break;
    }
    res = min(res, tp + lol(v, k, x + 1, 0));
  }
  return res;
}
map<char, int> mp;
int main() {
  mp['V'] = 1;
  mp['K'] = 2;
  string s;
  cin >> n;
  cin >> s;
  for (int i = 1; i <= n; i++) {
    int tp = mp[s[i - 1]];
    a[tp][Ln[tp]] = i;
    Ln[tp]++;
  }
  memset(dp, -1, sizeof(dp));
  cout << lol(0, 0, 0, 0) << endl;
  return 0;
}
