num = int(input()) dic = [] for x in range(num): m, s = input().split(' ') dic.append(s) for x in range(len(dic)): dic[x] = int(dic[x]) dic = sorted(dic, reverse = True) count = 0 for x in range(num-5): warn_num = 0 while dic[x+warn_num] != 0: for y in range(6): dic[x+y] -= 1 if dic[x+y] == 0: warn_num = y count += 1 dic[x+warn_num] = dic[x+5] print(count*5)