Find the next higher number with the same digits

//Code to find the next higher number with the same digits.
#include<iostream>
using namespace std;
int main()
{
 long long int m,n,A[1000],i,j,k,temp,same;
 cin>>n;
 same=0;
 i=0;
 while(n>0)
 {
  A[i]=n%10;
  n=n/10;
  i++; 
 } 
 //Finding the first digit at which the next digit is less than this digit starting from the left.
 for(j=0;j<i-1;j++)
 {
  if(A[j+1]<A[j])
  {
   //Finding the smallest digit greater than the pivotal digit.
   for(k=0;k<=j;k++)
   {
    if(A[k]>A[j+1])
    {
     break; 
    }
   }
   //Swapping the two digits.
   temp=A[k];
   A[k]=A[j+1]; 
   A[j+1]=temp; 
   same=1;
   break; 
  } 
 }
 //If the next higher number is possible with the same number of digits
 if(same==1)
 {
  m=A[i-1];
  for(k=i-2;k>j;k--)
  {
   m=m*10+A[k]; 
  }
  for(j=0;j<=k;j++)
  { 
   m=m*10+A[j]; 
  } 
 }
 //If the next higher number needs to have greater number of digits.
 else
 {
  m=A[0];
  m=m*10+A[0];
  for(j=1;j<i;j++)
  { 
   m=m*10+A[j]; 
  } 
 }
 cout<<m<<endl;
 fflush(stdin);
 getchar();
 return 0; 
}
Input: 37723971
Output: 37727139