def min_operations(s):
    n = len(s)
    operations = 0
    s_list = list(s)
    
    while True:
        bad_substrings = []
        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_list[k] == '0':
                        zeros += 1
                    else:
                        ones += 1
                if zeros >= ones:
                    bad_substrings.append((i, j))
        
        if not bad_substrings:
            return operations
        
        zero_frequency = {}
        for i in range(n):
            if s_list[i] == '0':
                count = sum(1 for start, end in bad_substrings if start <= i <= end)
                zero_frequency[i] = count
        
        if not zero_frequency:
            return -1
        
        best_pos = max(zero_frequency.items(), key=lambda x: x[1])[0]
        s_list[best_pos] = '1'
        operations += 1
    
    return operations