Sum of numbers

#include <iostream>
using namespace std;
int main (){
int n1,n2, suma=0;
cout << "\nI will ask to you two numbers and I will sum all the number that are in that range"<<endl;
cout << "\n Please give me the lower bound: ";
cin>>n1;
cout << "\n Please give me the higher bound: ";
cin>>n2;

    if(n1>n2){

      cout << "\nThe lower number that you give me is not the lower, is higher than the second number."<<endl;
      cout <<"\nTry to put the numbers in the correct order."<< endl;
    }

      else{

              do{

                  suma=suma+n1;
                  n1=n1+1;

              }while(n1<=n2);

cout <<"\nThe result of the sum is: " <<suma<<" "<<endl;
}



return 0;
}