Python program to remove duplicate characters of a given string.

def remove_duplicates(input_str):
    result = []
    seen_chars = set()

    for char in input_str:
        if char not in seen_chars:
            result.append(char)
            seen_chars.add(char)

    return ''.join(result)

# Example usage:
input_string = "abacabad"
output_string = remove_duplicates(input_string)
print(output_string)