G, C, P = map(int, input().split())
S = list(input())
N = len(S)

inf = 10 ** 18
pre = [[-inf] * 305 for i in range(305)]
pre[0][0] = 0
for i in range(N):
    dp = [[-inf] * 305 for i in range(305)]
    for g in range(G + 1):
        for c in range(C + 1):
            p = i - g - c
            if p < 0 or P < p:
                continue
            if S[i] == "G":
                dp[g + 1][c] = max(dp[g + 1][c], pre[g][c] + 1)
                dp[g][c + 1] = max(dp[g][c + 1], pre[g][c])
                dp[g][c] = max(dp[g][c], pre[g][c] + 3)
            elif S[i] == "C":
                dp[g + 1][c] = max(dp[g + 1][c], pre[g][c] + 3)
                dp[g][c + 1] = max(dp[g][c + 1], pre[g][c] + 1)
                dp[g][c] = max(dp[g][c], pre[g][c])
            else:
                dp[g + 1][c] = max(dp[g + 1][c], pre[g][c])
                dp[g][c + 1] = max(dp[g][c + 1], pre[g][c] + 3)
                dp[g][c] = max(dp[g][c], pre[g][c] + 1)
    dp, pre= pre, dp
print(pre[G][C])