#include <bits/stdc++.h>
#define N 85
using namespace std;
char s[N];
int n, cv, ck, co, pv[N], pk[N], po[N], uv[N], uk[N], uo[N], f[N][N][N][2];
void getmin(int &a, int b) { a = min(a, b); }
int main() {
  scanf("%d%s", &n, s);
  for (int i = 0; i < n; i++) {
    if (i != 0) {
      uo[i] = uo[i - 1];
      uv[i] = uv[i - 1];
      uk[i] = uk[i - 1];
    }
    if (s[i] == 86) {
      pv[cv++] = i, uv[i]++;
    } else if (s[i] == 75) {
      pk[ck++] = i, uk[i]++;
    } else {
      po[co++] = i, uo[i]++;
    }
  }
  memset(f, 0x3f, sizeof f);
  f[0][0][0][0] = 0;
  for (int i = 0; i <= cv; i++) {
    for (int j = 0; j <= ck; j++) {
      for (int k = 0; k <= co; k++) {
        int pos = i + j + k;
        for (int t = 0; t <= 1; t++) {
          if (i < cv) {
            getmin(f[i + 1][j][k][1],
                   f[i][j][k][t] + abs(uk[pv[i]] - j) + abs(uo[pv[i]] - k));
          }
          if (j < ck && !t) {
            getmin(f[i][j + 1][k][0],
                   f[i][j][k][t] + abs(uv[pk[j]] - i) + abs(uo[pk[j]] - k));
          }
          if (k < co) {
            getmin(f[i][j][k + 1][0],
                   f[i][j][k][t] + abs(uv[po[k]] - i) + abs(uk[po[k]] - j));
          }
        }
      }
    }
  }
  printf("%d\n", min(f[cv][ck][co][0], f[cv][ck][co][1]) / 2);
}