#include <bits/stdc++.h>
using namespace std;
const double pi = acos(0.0) * 2.0;
const long double eps = 1e-10;
const int step[8][2] = {{-1, 0}, {0, 1}, {1, 0},  {0, -1},
                        {-1, 1}, {1, 1}, {1, -1}, {-1, -1}};
template <class T>
inline T abs1(T a) {
  return a < 0 ? -a : a;
}
template <typename t, typename t1>
t min1(t a, t1 b) {
  return a < b ? a : b;
}
template <typename t, typename... arg>
t min1(t a, arg... arr) {
  return min1(a, min1(arr...));
}
template <typename t, typename t1>
t max1(t a, t1 b) {
  return a > b ? a : b;
}
template <typename t, typename... arg>
t max1(t a, arg... arr) {
  return max1(a, max1(arr...));
}
inline int jud(double a, double b) {
  if (abs(a) < eps && abs(b) < eps)
    return 0;
  else if (abs1(a - b) / max(abs1(a), abs1(b)) < eps)
    return 0;
  if (a < b) return -1;
  return 1;
}
template <typename t>
inline int jud(t a, t b) {
  if (a < b) return -1;
  if (a == b) return 0;
  return 1;
}
template <typename it, typename t1>
inline int find(t1 val, it a, int na, bool f_small = 1, bool f_lb = 1) {
  if (na == 0) return 0;
  int be = 0, en = na - 1;
  if (*a <= *(a + na - 1)) {
    if (f_lb == 0)
      while (be < en) {
        int mid = (be + en + 1) / 2;
        if (jud(*(a + mid), val) != 1)
          be = mid;
        else
          en = mid - 1;
      }
    else
      while (be < en) {
        int mid = (be + en) / 2;
        if (jud(*(a + mid), val) != -1)
          en = mid;
        else
          be = mid + 1;
      }
    if (f_small && jud(*(a + be), val) == 1) be--;
    if (!f_small && jud(*(a + be), val) == -1) be++;
  } else {
    if (f_lb)
      while (be < en) {
        int mid = (be + en + 1) / 2;
        if (jud(*(a + mid), val) != -1)
          be = mid;
        else
          en = mid - 1;
      }
    else
      while (be < en) {
        int mid = (be + en) / 2;
        if (jud(*(a + mid), val) != 1)
          en = mid;
        else
          be = mid + 1;
      }
    if (!f_small && jud(*(a + be), val) == -1) be--;
    if (f_small && jud(*(a + be), val) == 1) be++;
  }
  return be;
}
template <class T>
inline T lowb(T num) {
  return num & (-num);
}
inline int bitnum(unsigned int nValue) { return __builtin_popcount(nValue); }
inline int bitnum(int nValue) { return __builtin_popcount(nValue); }
inline int bitnum(unsigned long long nValue) {
  return __builtin_popcount(nValue) + __builtin_popcount(nValue >> 32);
}
inline int bitnum(long long nValue) {
  return __builtin_popcount(nValue) + __builtin_popcount(nValue >> 32);
}
inline int bitmaxl(unsigned int a) {
  if (a == 0) return 0;
  return 32 - __builtin_clz(a);
}
inline int bitmaxl(int a) {
  if (a == 0) return 0;
  return 32 - __builtin_clz(a);
}
inline int bitmaxl(unsigned long long a) {
  int temp = a >> 32;
  if (temp) return 32 - __builtin_clz(temp) + 32;
  return bitmaxl(int(a));
}
inline int bitmaxl(long long a) {
  int temp = a >> 32;
  if (temp) return 32 - __builtin_clz(temp) + 32;
  return bitmaxl(int(a));
}
long long pow(long long n, long long m, long long mod = 0) {
  if (m < 0) return 0;
  long long ans = 1;
  long long k = n;
  while (m) {
    if (m & 1) {
      ans *= k;
      if (mod) ans %= mod;
    }
    k *= k;
    if (mod) k %= mod;
    m >>= 1;
  }
  return ans;
}
template <class t1, class t2>
inline void add(t1 &a, t2 b, int mod = -1) {
  if (mod == -1) mod = 1000000007;
  a += b;
  while (a >= mod) a -= mod;
  while (a < 0) a += mod;
}
template <class t>
void output1(t arr) {
  for (int i = 0; i < (int)arr.size(); i++) cerr << arr[i] << ' ';
  cerr << endl;
}
template <class t>
void output2(t arr) {
  for (int i = 0; i < (int)arr.size(); i++) output1(arr[i]);
}
const int maxn = 80;
int dp[maxn][maxn][maxn][3];
char str[maxn];
int n;
int arr[maxn], cnt[3];
int bef[3][maxn][3];
int main() {
  ios_base::sync_with_stdio(0);
  scanf("%d%s", &n, str);
  for (int i = 0; i < n; i++) {
    if (str[i] == 'V')
      arr[i] = 0;
    else if (str[i] == 'K')
      arr[i] = 1;
    else
      arr[i] = 2;
    for (int j = 0; j < 3; j++) bef[arr[i]][cnt[arr[i]]][j] = cnt[j];
    cnt[arr[i]]++;
  }
  memset(dp, 0x3f, sizeof(dp));
  dp[0][0][0][2] = 0;
  for (int i = 0; i < n; i++) {
    for (int s0 = 0; s0 <= min(i, cnt[0]); s0++)
      for (int s1 = 0; s0 + s1 <= i && s1 <= cnt[1]; s1++)
        for (int last = 0; last < 3; last++) {
          int s2 = i - s0 - s1;
          if (s0 < cnt[0]) {
            int sbef = max(0, bef[0][s0][1] - s1) + max(0, bef[0][s0][2] - s2);
            dp[i + 1][s0 + 1][s1][0] =
                min(dp[i + 1][s0 + 1][s1][0], dp[i][s0][s1][last] + sbef);
          }
          if (s1 < cnt[1] && last != 0) {
            int sbef = max(0, bef[1][s1][0] - s0) + max(0, bef[1][s1][2] - s2);
            dp[i + 1][s0][s1 + 1][1] =
                min(dp[i + 1][s0][s1 + 1][1], dp[i][s0][s1][last] + sbef);
          }
          if (s2 < cnt[2]) {
            int sbef = max(0, bef[2][s2][0] - s0) + max(0, bef[2][s2][1] - s1);
            dp[i + 1][s0][s1][2] =
                min(dp[i + 1][s0][s1][2], dp[i][s0][s1][last] + sbef);
          }
        }
  }
  int ans = 1000000007;
  for (int i = 0; i < 3; i++) ans = min(dp[n][cnt[0]][cnt[1]][i], ans);
  cout << ans << endl;
  return 0;
}
