import sys

def main():
    raw_line = sys.stdin.read().strip()
    line = [int(x) for x in raw_line]

    blocks = []
    file_id = 0
    is_file_len = True
    for num in line:
        if is_file_len:
            if num > 0:
                blocks.extend([str(file_id)] * num)
                file_id += 1
        else:
            if num > 0:
                blocks.extend(["."] * num)
        is_file_len = not is_file_len

    # Move whole files in order of decreasing file ID
    max_file_id = file_id - 1
    for fid in range(max_file_id, -1, -1):
        file_positions = [i for i, b in enumerate(blocks) if b == str(fid)]
        if not file_positions:
            continue
        file_len = len(file_positions)
        leftmost_file_index = min(file_positions)

        candidate_spans = []
        free_count = 0
        start_index = 0
        for i in range(leftmost_file_index):
            if blocks[i] == '.':
                if free_count == 0:
                    start_index = i
                free_count += 1
                if free_count == file_len:
                    candidate_spans.append((start_index, i))
            else:
                free_count = 0

        if not candidate_spans:
            continue

        span_start, span_end = candidate_spans[0]

        for pos in file_positions:
            blocks[pos] = '.'
        for i in range(span_start, span_start + file_len):
            blocks[i] = str(fid)

    # Compute checksum
    checksum_parts = []
    for idx, val in enumerate(blocks):
        if val != ".":
            checksum_parts.append(idx * int(val))
    print("System Checksum Found: " + str(sum(checksum_parts)))

if __name__ == "__main__":
    main()