def min_operations(s):
    n = len(s)
    max_required = 0
    
    for i in range(n):
        for j in range(i+1, n):
            zeros = 0
            ones = 0
            
            for k in range(i, j+1):
                if s[k] == '0':
                    zeros += 1
                else:
                    ones += 1
            
            if zeros >= ones:
                required = zeros - ones + 1
                max_required = max(max_required, required)
    
    if max_required > s.count('0'):
        return -1
    
    return max_required