
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.NoSuchElementException;

public class Main {

	public static void main(String[] args) throws IOException {
		new Main().solve();
	}

	private void solve() throws IOException {
		try {
			//			solveA();
			//			solveB();
			solveC();
			//			 solveD();
			//			 solveE();
			//			 solveF();
		} finally {
			if (in != null) {
				in.close();
			}
			if (out != null) {
				out.flush();
				out.close();
			}
		}

	}

	private void solveA() {
		int numA = nextInt();
		int numB = nextInt();
		int numC = nextInt();

		if (numA == numB && numB == numC) {
			out.println("Yes");
		} else {
			out.println("No");
		}

	}

	private void solveB() {
		int numN = nextInt();
		char[] wk = next().toCharArray();

		int rCnt = 0;
		int bCnt = 0;
		for (int i = 0; i < numN; i++) {
			if (wk[i] == 'R') {
				rCnt++;
			} else if (wk[i] == 'B') {
				bCnt++;
			}
		}

		out.println(rCnt > bCnt ? "Yes" : "No");
	}

	private void solveC() {
		int boxNumN = nextInt();
		int magicNumQ = nextInt();
		char[] s = next().toCharArray();

		int[] goremBox = new int[boxNumN]; //箱
		int[] goremNum = new int[boxNumN]; //各箱のゴーレム
		Arrays.fill(goremNum, 1);
		for (int i = 0; i < goremBox.length; i++) {
			goremBox[i] = s[i] - 'a';
		}

		int[][] magic = new int[magicNumQ][2];

		for (int i = 0; i < magicNumQ; i++) {
			magic[i][0] = next().toCharArray()[0] - 'a';
			magic[i][1] = next().toCharArray()[0] == 'L' ? -1 : 1;
		}

		long res = goremNum.length;
		for (int i = 0; i < magicNumQ; i++) {
			int magicMove = magic[i][1];
			if (magicMove > 0) {
				for (int j = goremBox.length - 1; j >= 0; j--) {
					if (goremBox[j] == magic[i][0]) {
						if (j + 1 > goremNum.length - 1) {
							res -= goremNum[j];
						} else {
							goremNum[j + 1] = goremNum[j + 1] + goremNum[j];
						}
						goremNum[j] = 0;
					}
				}
			} else {
				for (int j = 0; j < goremBox.length; j++) {
					if (goremBox[j] == magic[i][0]) {
						if (j - 1 < 0) {
							res -= goremNum[j];
						} else {
							goremNum[j - 1] = goremNum[j - 1] + goremNum[j];
						}
						goremNum[j] = 0;
					}
				}
			}

		}

		out.println(res);
	}

	private void solveD() {
		int numN = nextInt();

		out.println("");
	}

	private void solveE() {
		int numN = nextInt();

		out.println("");
	}

	private void solveF() {
		int numN = nextInt();

		out.println("");
	}

	private final PrintWriter out = new PrintWriter(System.out);
	private final InputStream in = System.in;
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;

	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		} else {
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen <= 0) {
				return false;
			}
		}
		return true;
	}

	private int readByte() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	private void skipUnprintable() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
	}

	public boolean hasNext() {
		skipUnprintable();
		return hasNextByte();
	}

	public int nextInt() {
		return Integer.parseInt(next());
	}

	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if (!hasNext())
			throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}
}