import sys

#for line in sys.stdin:
#    print(line)
#    list = []
#    for char in line:
#        if char.isdigit():
#            list.append(int(char))
#    i=0 
#    j=1
#    while j< len(list):
#        print(tuple(list[i:j+1]))
#        i = i + 2
#        j = j + 2

i = int(input())
print(i+2)

#Testing the webhooks

