算某一天是这一年中的第几天

#include <math.h>
int ()
{
    int year,month,day,i,sum=0;
    int b[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
    while (scanf("%d/%d/%d",&year,&month,&day) != EOF){
        if((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))      
            b[2] = 29;                                  //闰年2月有29天
        else
            b[2] = 28;
        for(i = 1; i <= month - 1; i++)
            sum=sum+b[i];
        sum = sum + day;
        printf("%dn", sum);
        sum = 0;
    }
    return 0;
}