import bisect

def main():
    import sys
    input = sys.stdin.read().split()
    n = int(input[0])
    A = int(input[1])
    B = int(input[2])
    s = input[3]

    # Preprocess to find all 'con' runs
    runs = []
    i = 0
    while i <= len(s) - 3:
        if s[i:i+3] == 'con':
            count = 0
            j = i
            while j <= len(s) - 3 and s[j:j+3] == 'con':
                count += 1
                j += 3
            runs.append(count)
            i = j
        else:
            i += 1

    # We need to process the runs dynamically considering possible overlaps after operations
    # But we'll use a greedy approach with the sorted list
    available = sorted(runs)
    steps = 0
    current_step = 1  # 1-based steps

    while True:
        required = A if current_step % 2 == 1 else B
        if not available:
            break
        # Find the smallest run >= required
        idx = bisect.bisect_left(available, required)
        if idx == len(available):
            break  # no such run
        selected = available.pop(idx)
        remaining = selected - required
        if remaining > 0:
            bisect.insort(available, remaining)
        steps += 1
        current_step += 1

    print(steps)

if __name__ == '__main__':
    main()