C/C++ Program to convert mile into km and vice-versa

//Program to convert mile into km and vice-versa
#include<iostream>
using namespace std;
int main()
{
    double km,mile;
    int ch;
    cout<<"\n Enter your choice:";
    cout<<"\n\t 1. Convert KM into MILE \n\t 2.Convert MILE to KM"<<endl;
    cout<<"\n Enter  your choice :";
    cin>>ch;
    switch(ch)
         {
        case 1: cout<<"\n enter value to convert into MILE :";
            cin>>km;
            cout<<"\n "<<km<<" km = "<< km*0.621371<<" Mile approx."<<endl;
            break;
        case 2: cout<<"\n enter value to convert into KM :";
            cin>>mile;
            cout<<"\n "<<mile<<" Mile= "<<mile*1.60934<<" Km approx."<<endl;
            break;
        default: cout<<"\n Invalid option"<<endl;
            break;
         }
return 0;
}