PAT 1001 A+B Format （20 分) ——甲级

#include<iostream>
#include<string>
using namespace std;
int main(){
	int a, b, c;
	scanf("%d %d", &a, &b);
	c = a + b;
	if(c < 0){
		c = -1 * c;
		printf("-");
	}
	string str1 = to_string(c);
	string str2 = "";
	for(int i = str1.size()-1, j = 0; i >= 0; --i, ++j){
		if(j % 3 == 0 && j != 0)	str2 = ',' + str2;
		str2 = str1[i] + str2;
	}
	cout << str2 << endl;
	return 0;
}