运行成功,输出错误

#include <stdio.h>

int main() 

{ 

    /* 定义需要计算的日期 */

    int year = 2008;

    int month = 8;

    int day = 8;

    switch(month)

    {

    case 12:day+=30;

    case 11:day+=31;

    case 10:day+=31;

    case 9:day+=30;

    case 8:day+=31;

    case 7:day+=31;

    case 6:day+=30; 

    case 5:day+=31;  

    case 4:day+=30;

    case 3:day+=31;

    case 2:if(year%4==0&&year%400!=0)

    {day+=29;}else{day+=28;}

    case 1:day;

    printf("%d",day);

      break;

    }

    return 0;

}