View Code of Problem 101

#include<bits/stdc++.h>

using namespace std;

int main()
{
    string str;
    vector <char> a;
    vector <char> b;
    while(getline(cin,str)){
        for(int i = 0; i < str.size(); i++){
            if(str[i] <= '9' && str[i] >= '0'){
                a.push_back(str[i]);
            }
        }
            int count = 0;
            for (int i = a.size()-1; i >= 0 ; i--){
                count++;
                if(count % 3 == 0 && i != 0){
                     b.push_back(a[i]);
                     b.push_back(',');
                }
                else
                    b.push_back(a[i]);
            }
            for(int i = b.size() - 1; i >= 0; i--){
                cout<< b[i];
            }
            cout<<endl;
            a.clear();
            b.clear();
    }
    return 0;
}