def chmax(DP,i,v):
    if DP[i] < v: DP[i] = v

def main():
    G, C, P = list(map(int, input().split()))
    S2 = list(input())
    N = len(S2)
    S = []
    for s in S2:
        if s == 'G':
            S.append(0)
        elif s == 'C':
            S.append(1)
        else:
            S.append(2)

    def judge(yuki, friend):
        diff = (friend - yuki)%3
        if diff == 1:
            res = 3
        elif diff == 2:
            res = 0
        else:
            res = 1
        return res

    dp = [[-1] * (C + 1) for _ in range(G + 1)]
    dp[0][0] = 0

    for i in range(N):
        friend = S[i]
        pre = [[-1] * (C + 1) for _ in range(G + 1)]
        dp, pre = pre, dp
        for j in range(G + 1):
            for k in range(C + 1):
                val = pre[j][k]
                if val == -1:
                    continue
                # これまで全部でi個使った
                # G ... j
                # C ... k
                # P ... i - j - k

                # G を出す
                # 寄与先・・dp[i + 1][j + 1][k]
                if j + 1 <= G:
                    chmax(dp[j + 1], k, val + judge(0, friend))
                # C を出す
                # dp[i + 1][j][k + 1]
                if k + 1 <= C:
                    chmax(dp[j], k + 1, val + judge(1, friend))

                # P を出す 今 i - j - k だけど、上限に達していない？
                if i - j - k < P:
                # dp[i + 1][j][k]
                    chmax(dp[j], k, val + judge(2, friend))
    ans = 0
    for j in range(G + 1):
        for k in range(C + 1):
            ans = max(ans, dp[j][k])
    print(ans)

if __name__ == "__main__":
    main()