all_of_them = []
current = 0

with open("1_1.in") as fh:
    for line in fh:
        line = line.strip()
        if not line:
            all_of_them.append(current)
            current = 0
            continue

        current += float(line)

all_of_them.sort(reverse=True)
print(sum(all_of_them[:3]))