#!/usr/bin/env python3
h,d,a=0,0,0
for c,s in(x.strip().split()for x in open("input.txt")):v=int(s);h,d,a=(h+v,d+a*v,a)if c[0]=='f'else(h,d,a+(-v if c=='up'else v))
print(h*d)