#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
long long POW(long long a, long long b, long long MMM = MOD) {
  long long ret = 1;
  for (; b; b >>= 1, a = (a * a) % MMM)
    if (b & 1) ret = (ret * a) % MMM;
  return ret;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) {
  if (a == 0 || b == 0) return a + b;
  return a * (b / gcd(a, b));
}
int dx[] = {0, 1, 0, -1, 1, 1, -1, -1}, dy[] = {1, 0, -1, 0, 1, -1, 1, -1};
int n, m, k;
int a[51], d[51][2001];
char s[52];
int go(int N, int K) {
  if (K >= k) return 0;
  int &ret = d[N][K];
  if (ret != -1) return ret;
  ret = 2000000005;
  for (int(i) = (1); (i) <= (n); (i) += (1))
    if (a[i] > a[N] && s[i] != s[N])
      ret = min(ret, (N == 0 ? abs(m - i) : abs(N - i)) + go(i, K + a[i]));
  return ret;
}
int main() {
  memset((d), -1, sizeof(d));
  ;
  scanf("%d%d%d", &n, &m, &k);
  for (int(i) = (1); (i) <= (n); (i) += (1)) scanf("%d", a + i);
  scanf("%s", s + 1);
  int ans = go(0, 0);
  if (ans == 2000000005) ans = -1;
  printf("%d", ans);
}
