It is perfectly OK to put one block inside another, indeed you will need to do this if you want to make complex decisions in your program. On the right you can see this in action.

Note that I am still using indenting to indicate the way in which code is dependent on which condition. Note also that I have made sure that I have the same number of { characters as I have }s. Note also that I could have added some else items and this would still make sense.

if ( condition ) {
    /* start a block */
    Statements to be performed ;
    if condition is true ;
}   /* end a block */
else {
    Statements to be performed ;
    if condition is false ;
}