a = "viet nam"

b = "a"

print(len(a))

print(a.find(b))

def tong(n):

       if n <= 0:

           print("vui long nhap mot ssso nguyen duong.")

           return 0

   a = 0

   while n > 0:

        a = a + n % 10

        n / /= 10

   return a

n = int(input("nhap so nguyen duong n: "))

print(f"tong cac chu so cua {n} la:", tong(n))

ket qua in ra man hinh la 1 2 3 4 5

1 2

2 4

3 6

4 8

5 10

6 12

7 14

8 16

9 18

10 20

n = int(input("nhat so nguyen n: "))

s = 0

for i in range(n):

      if 1 % 2 == 0 and 1 % 5 == 0:

          s = s + 1

print(f"tinh tong so tu nhien nho hon {n} va chia het cho 2 va 5: {s}

a = float(input("nhap moy so thuc a: "))

if a >= 0:

    print(f"gia tri tuyet doi cua {a} la {a}")

else:

      print(f"giatri tuyet doi cua {a} la {-a}")