[백준 1373] 2진수 8진수

#include<iostream>
#include<string>
using namespace std;
int main(void)
{
    string s;
    cin>>s;
    int n=s.size();
    
    if (n%3 == 1)
        cout<<s[0];
    else if (n%3 == 2)
        cout<<(s[0]-'0')*2+(s[1]-'0');
    for(int i=n%3; i<n; i+=3)
        cout << (s[i]-'0')*4 + (s[i+1]-'0')*2 + (s[i+2]-'0');
    cout<<'\n';
    return 0;
}