Battle Ships

n = int(input())
ships = 0
rows = []

for i in range(n):
    row = [int(x) for x in input().split()]
    rows.append(row)

squares = input().split()

for spot in squares:
    spot = [int(x) for x in spot.split('-')]
    row_place = spot[0]
    col_place = spot[1]
    if rows[row_place][col_place] > 0:
      rows[row_place][col_place] -= 1
      if rows[row_place][col_place] == 0:
        ships += 1

print(ships)