Regarding mergesort

sir,
In this when I am running code thos shows runtime error,
I am providing my ide.https://ide.codingblocks.com/s/81730

Raushan error is coming due to array size
and dont do a[n] gave it a fixed size or allocate it dynamically it can gave error sometime

Also ur code of merge sort is wrong ans u have to split the original array into 2 half array which u compare for merging and then call the mersort func

Now I have fix the size of array in it but in this time it gives same error. so, please check the code once more because it runs on my system but shows problem only over here.Also I have submitted others code problems yesterday or day before yesterday but the doubt has not been resolved.