>>299
#include <stdio.h>
#include <time.h>

int main(void)
{
　struct tm tm, tm2;
　int y, m, d;

　printf("西暦と年月日を入力して下さい:");
　scanf("%d %d %d", &y, &m, &d);

　tm.tm_year = 2000 - 1900;
　tm.tm_mon = 12 - 1;
　tm.tm_mday = 31;
　tm.tm_hour = 0;
　tm.tm_min = 0;
　tm.tm_sec = 0;
　tm.tm_isdst = 0;

　tm2.tm_year = y - 1900;
　tm2.tm_mon = m - 1;
　tm2.tm_mday = d;
　tm2.tm_hour = 0;
　tm2.tm_min = 0;
　tm2.tm_sec = 0;
　tm2.tm_isdst = 0;

　printf("%ld days\n", (long)difftime(mktime(&tm), mktime(&tm2)) / (60 * 60 * 24));
　return 0;
}