View Code of Problem 101

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int main(){
    char a[999],b[999],c[999];
    int k,t,m;
    while(cin>>a){
        k=0,t=0,m=0;
        memset(c,0,sizeof(c));
        for(int i=0;i<strlen(a);i++){
            if(a[i]>='0'&&a[i]<='9')
                b[k++]=a[i];
        }
        for(int i=k-1;i>=0;i--){
            if(t%3==0&&t!=0){
                c[m++]=',';
                t=0;
                i++;
            }
            else{
            c[m++]=b[i];
                t++;}
        }
        for(long int i=strlen(c)-1;i>=0;i--){
            cout<<c[i];
        }
        cout<<endl;
    }
    return 0;
}