#include <bits/stdc++.h>
using namespace std;
#ifdef MIKU
#define debug(x...) cout << "[" << #x << "] : ", dout(x)
void dout() { cout << endl; }
template <typename T, typename ...U>
void dout(T t, U ...u) { cout << t << (sizeof...(u) ? ", " : ""); dout(u...); }
#else
#define debug(...) 39
#endif
#define int long long
#define fs first
#define sc second
#define mp make_pair
#define FOR(i, j, k) for (int i = j, Z = k; i < Z; i++)
typedef pair<int, int> pii;
const int MXN = 7005;
int n, m, q, a[MXN];
string s;
void DO(int sr) {
debug(sr);
s[sr] = 'R';
vector<int> B, R;
FOR(i, sr + 1, n) if (s[i] == 'B') B.push_back(i);
for (int i = sr - 1; i >= 0; i--) if (s[i] == 'R') R.push_back(i);
if (B.size() > R.size()) {
FOR(i, 0, B[R.size()] + 1) s[i] = 'R';
} else {
if (B.empty()) FOR(i, sr, n) s[i] = 'B';
else FOR(i, R[B.size() - 1], n) s[i] = 'B';
}
debug(s);
}
void miku() {
int l, r;
cin >> n >> m >> s;
if (n > MXN || m > MXN) return;
FOR(i, 1, m + 1) cin >> a[i];
cin >> q;
if (q > 1) return;
cin >> l >> r;
FOR(i, l, r + 1) DO(a[i] - 1);
int ans = 0;
for (auto &i : s) ans += (i == 'R');
cout << ans << '\n';
}
int32_t main() {
cin.tie(0) -> sync_with_stdio(false);
cin.exceptions(iostream::failbit);
miku();
return 0;
}
