Convert Octal to Binary

#include <iostream>
#include <cmath>
using namespace std;

int octalToDecimal(long long octal) {
    int decimal = 0, i = 0, remainder;
    while (octal != 0) {
        remainder = octal % 10;
        octal /= 10;
        decimal += remainder * pow(8, i);
        ++i;
    }
    return decimal;
}

long long decimalToBinary(int decimal) {
    long long binary = 0;
    int remainder, i = 1;
    while (decimal != 0) {
        remainder = decimal % 2;
        decimal /= 2;
        binary += remainder * i;
        i *= 10;
    }
    return binary;
}

int main() {
    long long octal;
    cout << "Enter an octal number: ";
    cin >> octal;
    
    int decimal = octalToDecimal(octal);
    long long binary = decimalToBinary(decimal);
    
    cout << "Octal: " << octal << " = Binary: " << binary << endl;
    
    return 0;
}