n = 10**8
print("We want to compute 1+2+3+...+", n)
print("We want to compute 1+2+3+...+" + str(n))



print("Using while loop:")
i = 1
s = 0
while i<=n:
    s = s+i
    i = i+1
    #print("i=", i, "s=", s)
print(s)


print("Using for loop + range:")
s = 0
for i in range(1,n+1,1):
    s = s+i
print(s)


print("Using Python's built-in sum")
print(sum(range(1,n+1,1)))
      

print("Using Gauss' formula")
print((n*(n+1)//2))