set in resistor

#include<iostream>

#include<iomanip>

using namespace std;

int main()

{

    int res1,res2,res3;

    double a=1.0;

    cout<<fixed<<showpoint;

    cout<<"enter first resistor:"<<endl;

    cin>>res1;

    cout<<"enter second resistor:"<<endl;

    cin>>res2;

    cout<<"enter third resistor:"<<endl;

    cin>>res3;

    

    double resistance;

    resistance=a/((a/res1)+(a/res2)+(a/res3));

    

    cout<<setprecision(1)<<endl;

    cout<<"The combined resistance is"<<setw(3)<<resistance<<"ohms"<<endl;

        return 0;

    }