import java.io.IOException;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Main {
	char[] s;
	int[][][] dp;
	int[][] score;

	int dp(int k, int g, int c) {
		if (s.length <= k) {
			return 0;
		}
		if (0 <= dp[k][g][c]) {
			return dp[k][g][c];
		}

		int res = 0;
		if (0 < g) {
			res = Math.max(res, dp(k + 1, g - 1, c) + score['G'][s[k]]);
		}
		if (0 < c) {
			res = Math.max(res, dp(k + 1, g, c - 1) + score['C'][s[k]]);
		}
		if (0 < s.length - g - c - k) {
			res = Math.max(res, dp(k + 1, g, c) + score['P'][s[k]]);
		}
		return dp[k][g][c] = res;
	}

	void run() {
		MyScanner sc = new MyScanner();
		score = new int['Z']['Z'];
		score['G']['G'] = 1;
		score['G']['C'] = 3;
		score['G']['P'] = 0;
		score['C']['G'] = 0;
		score['C']['C'] = 1;
		score['C']['P'] = 3;
		score['P']['G'] = 3;
		score['P']['C'] = 0;
		score['P']['P'] = 1;

		int g = sc.nextInt();
		int c = sc.nextInt();
		int p = sc.nextInt();
		s = sc.next().toCharArray();

		dp = new int[s.length][g + 1][c + 1];
		for (int i = 0; i < s.length; i++) {
			for (int j = 0; j < g + 1; j++) {
				Arrays.fill(dp[i][j], -1);
			}
		}
		System.out.println(dp(0, g, c));
	}

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

	public void mapDebug(int[][] a) {
		System.out.println("--------map display---------");
		for (int i = 0; i < a.length; i++) {
			for (int j = 0; j < a[i].length; j++) {
				System.out.printf("%3d ", a[i][j]);
			}
			System.out.println();
		}
		System.out.println("----------------------------" + '\n');
	}

	class MyScanner {
		int read() {
			try {
				return System.in.read();
			} catch (IOException e) {
				throw new InputMismatchException();
			}
		}

		boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		boolean isEndline(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

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

		int[] nextIntArray(int n) {
			int[] array = new int[n];
			for (int i = 0; i < n; i++)
				array[i] = nextInt();
			return array;
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		long[] nextLongArray(int n) {
			long[] array = new long[n];
			for (int i = 0; i < n; i++)
				array[i] = nextLong();
			return array;
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		double[] nextDoubleArray(int n) {
			double[] array = new double[n];
			for (int i = 0; i < n; i++)
				array[i] = nextDouble();
			return array;
		}

		String next() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		String[] nextStringArray(int n) {
			String[] array = new String[n];
			for (int i = 0; i < n; i++)
				array[i] = next();

			return array;
		}

		String nextLine() {
			int c = read();
			while (isEndline(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndline(c));
			return res.toString();
		}
	}
}