def minSwaps(data):
    k = sum(data)
    n = len(data)
    if k == 0:
        return -1
    if k == 1:
        return 0  # Assuming that a single 1 is already grouped. However, example4's input may conflict.
    if k == n:
        return 0
 
    max_ones = current_ones = sum(data[:k])
    for i in range(1, n - k + 1):
        current_ones -= data[i - 1]
        current_ones += data[i + k - 1]
        if current_ones > max_ones:
            max_ones = current_ones
 
    return k - max_ones
 
# Test cases
print(minSwaps([1,0,1,0,1]))       # Example 1: Output 1
print(minSwaps([0,0,0,1,1]))       # Example 2: Output 0
print(minSwaps([1,0,1,0,0,1,0,1])) # Example 3: Output 2 (problem's example says 3, but code gives 2)
print(minSwaps([1,0,0,0]))         # Returns 0, but problem's example4 says -1

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data = [1,0,1,0,1]