def sumab(a,b): return (a+b)*(b-a+1)//2 return sum ( range(a,b+1)) # res =0 # for i in range(a,b+1): # res +=i # return res a = sumab(1,10) print(a) a = sumab(20,30) print(a) a = sumab(35,45) print(a)