PAT 甲级 1001 A+B Format

-1000000 9

#include <iostream>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <math.h>
#include <stdio.h>
#include <string>
#include <vector>
#include <strstream>

using namespace std;
int a,b;
int main()
{
	while(scanf("%d%d",&a,&b)!=EOF)
	{
		int num=a+b;
		strstream ss;
		string s;
		ss << num;
		ss >> s;
		int len=s.length();
		if(num<0)
			num=(len-1)%3;
		else
			num=len%3;
		for(int i=0;i<num;i++)
		{
			cout<<s[i];
			if(s[i]=='-') num++;
			if(i==num-1&&len>3)
				cout<<",";
		}
		int cnt=0;
		for(int i=num;i<len;i++)
		{
			cout<<s[i];
			if(s[i]<='9'&&s[i]>='0')
				cnt++;
			if(cnt==3)
			{
				if(i!=len-1)
					cout<<",";
				cnt=0;
			}
		}
		cout<<endl;
	}
}