Calculate julian day for one year in fortran - fortran

Question

I want to calculate julian day for just one year (not from 4713 BC!). For example, If it is 3 of March, it will give as a result the number 62 If February has 28 days, and 63 if it has 29. Until now, I have written the following code in Fortran 95, which unfortunately gives wrong result. Could you please help me debug it?
program task
!============================
!filename: task.f95
implicit none
integer day, sum_month, i, month(12), jd, year, mon
month = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
write(6,*) "Give day"
read(5,*) day
write(6,*) "Give mon"
read(5,*) mon
write(6,*) "Give year"
read(5,*) year
sum_month = 0
if (mod(year,4)==0 .and. mod(year,100)/=0) then
do i = month(1), mon-1
sum_month = sum_month + month(1) + day + 1
end do
else
do i = month(1), mon-1
sum_month = sum_month + month(1) + day
end do
end if
write(6,*) sum_month
end program task

Answer 1

This loop
do i = month(1), mon-1
sum_month = sum_month + month(1) + day + 1
end do
and the other one like it, is seriously broken. Every time you call it month(1)==31 and mon is likely to be between 1 and 12 (inclusive). So the program will try to execute, for (for example) mon==12
do i = 31,12
and under the rules of Fortran this loop will execute 0 times. I'm almost certain you should write:
do i = 1, mon-1
sum_month = sum_month + month(i) ...
Fix that, sort out the rest of your code, and you'll probably fix it without further help.
EDIT:
Your code is getting worse ! Well, it was getting worse until VladimirF rolled back your latest changes. Do as he and I have suggested. Ask a new question concerning your current problem.
You're not being careful enough about the difference between your variable mon (which you use to hold the number of the month input by the user) and month (which is the array you use to hold the number of days in each month of the year).
These statements
write(6,*) "Give mon"
read(5,*) month(i)
will read the value which belongs in mon and put it into month(i). Or rather, that's what it tries to do but at that place in the code i doesn't have any value and the code attempts to write it into some arbitrary location in the computer's memory -- this is what a segmentation fault is and this is a great way to generate one. Don't do that !
You're going to have a problem later too, when your code reaches
do i = 1, month(i)-1
Go back to the top of my answer and ask yourself What value does month(i) have when this line of code is executed ?