N = int(input())

M_list = []

K = 0

for i in range(N):
    T, S = input().split(' ')
    T = int(T)
    kukan = len(S)
    K += kukan
    taka = 12 * T // 1000
    if kukan > taka:
        m = kukan - taka  #それぞれの区間でのミス
        M_list.append(m)
        M = sum(M_list)  #ミスの合計

A = K - M
print(A)