def add(a,b) :
	c=a+b;
	return c;

def sub():
	a=int(input("Enter first value : "));
	b=int(input("Enter second value : "));
	c=a-b;
	print(a,"-",b,"is : ",c);

print(add(10,20));
print(add(20,20));
print(add(30,20));

sub();