battle_ships

rows = int(input())

destroyed = 0
field = []
for i in range(rows):
    field.append(list(map(int, input().split())))

attack = input().split()

for j in range(len(attack)):
    current_attack = attack[j].split("-")
    curr_row = int(current_attack[0])
    curr_col = int(current_attack[1])

    if field[curr_row][curr_col] > 0:
        field[curr_row][curr_col] -= 1
        if field[curr_row][curr_col] == 0:
            destroyed += 1

print(destroyed)