#!/usr/bin/env python3
import sys

depth = 0
horiz = 0
aim = 0

for l in sys.stdin:
    comm, val = l.split()
    if comm == "down":
        aim += int(val)
    elif comm == "up":
        aim -= int(val)
    elif comm == "forward":
        horiz += int(val)
        depth += aim * int(val)
    else:
        raise Exception(f"bad comm: {comm}")

print(horiz * depth)