请各位指教一下，如果用scanf语句 这个有什么问题么？

#include <stdio.h>

int main()

{

    /* 定义需要计算的日期 */

    int year;

    int month;

    int day;

    printf("请输入年月日\n");

    scanf_s("%d,%d,%d",&year,&month,&day);

    int sum;

    switch (month)

    {

    case 1:sum = 0; break;

        case 2:sum = 31; break;

        case 3:sum = 59; break;

        case 4:sum = 89; break;

        case 5:sum = 120; break;

        case 6:sum = 150; break;

        case 7:sum = 181; break;

        case 8:sum = 212; break;

        case 9:sum = 242; break;

        case 10:sum = 273; break;

        case 11:sum = 303; break;

        case 12:sum = 334; break;

        default:printf("一年中只有十二个月哦");

    }

    if (year % 400 ==0 || year % 4 ==0 && year%100 != 0)

    {

        if (month > 2)

        {

            sum = sum + day + 1;

        }

        else

                {  

            sum = sum + day;

                } 

        printf("%d年%d月中的第%d天\n",year,month ,sum);

    }

    return 0;

}