#include <iostream>

using namespace std;

void merge(int arr[],int l, int mid, int r){

int n1 = mid-l+1;

int n2 = r-mid;

int a[n1];

int b[n2];

for(int i = 0; i<n1; i++){

a[i] = arr[l+i];

};

for(int i=0; i<n2;i++){

b[i] = arr[mid+1+i];

}

int i=0;

int j=0;

int k = l;

while(i<n1 && j<n2){

if(a[i]<b[j]){

arr[k] = a[i];

k++;

i++;

}else{

arr[k]=b[j];

k++;

j++;

}

}

while(i<n1){

arr[k] = a[i];

k++;

i++;

}

while(i<n2){

arr[k] = b[j];

k++;

j++;

}

}

void mergeSort(int arr[],int l,int r){

if(l<r){

int mid = (l+r)/2;

mergeSort(arr,l,mid);

mergeSort(arr,mid+1,r);

merge(arr,l,mid,r);

}

}

int main(){

int arr[] = {5,4,3,2,1};

mergeSort(arr,0,4);

for(int i=0; i<5;i++){

cout << arr[i] << " ";

}

cout << endl;

return 0;

}