# Enter your code here. Read input from STDIN. Print output to STDOUT
def longest_segment(A, L):
    n = len(A)
    C = [None] * (n + 1)
    M = [None] * (n + 1)
    M[0] = C[0] = x = y = 0
    for i in range(1, n + 1):
        C[i] = C[i - 1] + A[i - 1]
        if C[i - 1] < C[M[i - 1]]:
            M[i] = i - 1
        else:
            M[i] = M[i - 1]
        k = i - y + x - 1
        while k > 0:
            if C[i] - C[M[k]] >= L:
                k = M[k]
            else:
                break
            x, y = k + 1, i
    return 0 if y == 0 else y - x + 1

def max_prefix(s):
    m, t = 0, 0
    for v in s:
        t += v
        m = max(m, t)
    return m

def numeric(s): return list(map(lambda x: 3 if x == '1' else -2, s))

def solve(k, s):
    n = len(s)
    s = numeric(s)
    d = sum(s)
    if d >= 0: return k * n
    d = -d
    mh = max_prefix(s)
    mt = max_prefix(reversed(s))
    r = longest_segment(s, 0)
    if k > 1:
        mult = min((mh + mt) // d, k - 2)
        r = max(r, mult * n + longest_segment(s * 2, mult * d))
    return r
    
k, s = input().split()
print(solve(int(k), s))