program series

implicit none

!program obliczajacy sume szeregu
! \sum_{i=0}^{\infinity} (-1)^i \frac{1}{2*i+1}

integer :: i, max
real :: suma

write(*,*)'Ile wyrazow dodac?'
read(*,*)max

suma = 0.0

do i = 0, max

   suma = suma + ((-1.0)**i)*(1.0/(2*i+1))

end do

write(*,*) 'Suma wynosi', suma

end