5-3

#include<stdio.h>
#include<string.h>
#define WEEK_PER 7
int main(void)
{
int day,week,days;
printf("please input day\n");
scanf("%d",&day);
while(day>0){
week=day/WEEK_PER;
days=day%WEEK_PER;
printf("%d days are %d weeks,%d days.\n",day,week,days);
scanf("%d",&day);
}

return 0;
}