list_year=[] count=0 for i in range(5):

list_year+=(list(map(int,input().split())))
for i in list_year:

if i>9999 and i<1000:
    continue
elif (i//1000)==((i%100)//10) and (i%1000//100)+1==(i%10):
        count+=1
else:
    break
print(count)