3.1

#include<iostream>
using namespace std;
int sum(int n,int m)
{
    if(n==m)
        return m;
    else
        return (n+sum(n+1,m));
}
int main()
{
    cout<<"enter the range:";
    int n,m;
    cin>>n;
    cin>>m;
   
    int total=sum(n,m);
    cout<<"sum is :"<<total<<endl;
    return 0;
}