merge sort

def merge(l,r,a):
    if(l<r):
        mid=(l+r)//2
        merge(l,mid,a)
        merge(mid+1,r,a)
        mergesort(l,mid,r,a)
def mergesort(l,mid,r,a):
    L=a[l:mid+1]
    R=a[mid+1:r+1]
    i=j=0
    k=l
    while i<len(L) and j<len(R):
        if L[i]<R[j]:
            a[k]=L[i]
            i+=1
        else:
            a[k]=R[j]
            j+=1
        k+=1
   
    while i<len(L):
        a[k]=L[i]
        i+=1
        k+=1
    while j<len(R):
        a[k]=R[j]
        j+=1
        k+=1
    
        
a=[64, 34, 25, 12, 22, 11, 90]
merge(0,len(a)-1,a)
print(a)