import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

N = int(readline())
data = readlines()

answer = 0
for line in data:
    t,s = line.split()
    t = int(t)
    L = len(s)
    x = t * 12 // 1000
    answer += min(x,L)

print(answer)