#include <bits/stdc++.h>
using namespace std;
int dp[4][55][55][2005];
int r[55];
char c[55];
int main() {
  memset(dp, -1, sizeof(dp));
  int n, s, k;
  scanf("%d%d%d", &n, &s, &k);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &r[i]);
  }
  scanf("%s", c + 1);
  for (int i = 1; i <= n; i++) {
    if (c[i] == 'R')
      c[i] = 0;
    else if (c[i] == 'B')
      c[i] = 1;
    else
      c[i] = 2;
  }
  queue<pair<pair<int, int>, pair<int, int> > > q;
  dp[3][s][0][0] = 0;
  q.push(pair<pair<int, int>, pair<int, int> >(pair<int, int>(3, s),
                                               pair<int, int>(0, 0)));
  int ans = 2e9;
  while (!q.empty()) {
    int color = q.front().first.first;
    int u = q.front().first.second;
    int candy = q.front().second.first;
    int tot = q.front().second.second;
    q.pop();
    if (tot == k) ans = min(ans, dp[color][u][candy][tot]);
    int vcolor = color;
    int v = u - 1;
    int vcandy = candy;
    int vtot = tot;
    if (v >= 1 && v <= n) {
      if (dp[vcolor][v][vcandy][vtot] == -1 ||
          dp[vcolor][v][vcandy][vtot] > dp[color][u][candy][tot] + 1) {
        dp[vcolor][v][vcandy][vtot] = dp[color][u][candy][tot] + 1;
        q.push(pair<pair<int, int>, pair<int, int> >(
            pair<int, int>(vcolor, v), pair<int, int>(vcandy, vtot)));
      }
    }
    v = u + 1;
    if (v >= 1 && v <= n) {
      if (dp[vcolor][v][vcandy][vtot] == -1 ||
          dp[vcolor][v][vcandy][vtot] > dp[color][u][candy][tot] + 1) {
        dp[vcolor][v][vcandy][vtot] = dp[color][u][candy][tot] + 1;
        q.push(pair<pair<int, int>, pair<int, int> >(
            pair<int, int>(vcolor, v), pair<int, int>(vcandy, vtot)));
      }
    }
    if (c[u] != color && r[u] > candy) {
      vcolor = c[u];
      v = u;
      vcandy = r[u];
      vtot = min(tot + r[u], k);
      if (v >= 1 && v <= n) {
        if (dp[vcolor][v][vcandy][vtot] == -1 ||
            dp[vcolor][v][vcandy][vtot] > dp[color][u][candy][tot]) {
          dp[vcolor][v][vcandy][vtot] = dp[color][u][candy][tot];
          q.push(pair<pair<int, int>, pair<int, int> >(
              pair<int, int>(vcolor, v), pair<int, int>(vcandy, vtot)));
        }
      }
    }
  }
  if (ans == 2e9) ans = -1;
  printf("%d\n", ans);
}
