What is wrong with this if else statement?

I'm working with Ada, and the lack of braces on the control statements have been getting me a bit mixed up. I have written the following if-else statement:

if i = 1 then
    largest := nextInteger;
else if i = 2 then
    if nextInteger > largest then
        secondLargest := largest;
        largest := nextInteger;
    else
        secondLargest := nextInteger;
    end if;
else
    if nextInteger > largest then
        secondLargest := largest;
        largest := nextInteger;
    else if largest > nextInteger and then nextInteger > secondLargest then
        secondLargest := nextInteger;
    end if;
end if;

The error message that I get is:

program_one.adb:15:05: missing "end if:" for "if" at line 3
program_one.adb:15:05: missing "end if;" for "if" at line 1

I'm struggling to find where I didn't close out an if statement. It's late and I've been working all day, so I may just be tired. Can anyone help?