Binary to decimal

Number system conversion
Input a 4-digit binary number, convert it to a decimal number and output it.
For example: input 1101 from the keyboard,
so the program should output 13

#include<bits/stdc++.h>

using namespace std;

int ss(int x, int n)
{
    
    
    int sum = 1;
    while(n--)
    {
    
    
        sum = sum * 2;
    }
    return sum * x;
}


int main()
{
    
    
    int x;
    int sum = 0;
    cin>>x;
    for(int i = 0; i <= 3; i++)
    {
    
    
        int k = x % 10;
        sum = sum + ss(k, i);
        x = x / 10;
    }
    cout<<sum<<endl;
}