View Code of Problem 101

#include<iostream>
#include<cstring>
#include<math.h>
using namespace std;
int main(){
	string s;
	while(cin>>s){
		string m;
		int k=0,num=0;
		for(int i=s.length()-1;i>=0;i--){
			if(s[i]==',')continue;
			m[k++]=s[i];
			num++;
			if(num%3==0&&i!=0){
				m[k++]=',';
			}
			
		}
		for(int i=k-1;i>=0;i--){
			cout<<m[i];
		}
		cout<<endl;
	}
	return 0;
}