Find the time complexity of sum of two numbers

What is the time complexity of the program for the sum of two numbers ?

Step count method

void main() 

{

int a,b,c; //----------0

a=10; //----------1

b=20; //----------1

c=a+b; //----------1

}

f(n) = 0+1+1+1 = 3

f(n) = O(1)