#include <stdio.h>
int allzero(int* list) {
  int size = 7;

  int total = 0, i;
  for (i = 0; i < size; i++) {
    printf("%d, %d\n", i, list[i]);
    if (list[i] == 0) {
      total++;
    }
  }
  if (total == size) {
    printf("All zeros\n");
  }
  return 0;
}

int isLeapYear(int year) {
  return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
}

int monthDays(int month, int year) {
  int month_days[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  return month == 2 && isLeapYear(year) ? 29 : month_days[month - 1];
}

int daysBetween(int start_month, int start_day, int start_year, int end_month,
                int end_day, int end_year) {
  int days = 0;

  // sanitize month inputs
  if (start_month < 1) start_month = 1;
  if (end_month < 1) end_month = 1;
  if (start_month > 12) start_month = 12;
  if (end_month > 12) end_month = 12;

  // sanitize day inputs
  if (start_day < 1) start_day = 1;
  if (end_day < 1) end_day = 1;
  if (start_day > monthDays(start_month, start_year))
    start_day = monthDays(start_month, start_year);
  if (end_day > monthDays(end_month, end_year))
    end_day = monthDays(end_month, end_year);

  // swap dates if start date before end date
  int swapDates = 0;
  if (end_year < start_year) {
    swapDates = 1;
  }
  if (end_year == start_year) {
    if (end_month < start_month) {
      swapDates = 1;
    }
  }
  if (end_year == start_year) {
    if (end_month == start_month) {
      if (end_day < start_day) {
        swapDates = 1;
      }
    }
  }
  if (swapDates) {
    int t = end_month;
    end_month = start_month;
    start_month = t;
    t = end_day;
    end_day = start_day;
    start_day = t;
    t = end_year;
    end_year = start_year;
    start_year = t;
  }

  // calculate days
  if (start_month == end_month) {
    if (start_year == end_year) {
      days = end_day - start_day;
    }
  } else {
    days += monthDays(start_month, start_year) - start_day;
    days += end_day;
    if (start_year == end_year) {
      int month = start_month + 1;
      while (month < end_month) {
        days += monthDays(month, start_year);
        month++;
      }
    } else {
      int year;
      int month = start_month + 1;
      while (month <= 12) {
        days += monthDays(month, start_year);
        month++;
      }
      month = 1;
      while (month < end_month) {
        days += monthDays(month, end_year);
        month++;
      }
      year = start_year + 1;
      while (year < end_year) {
        days += 365;
        if (isLeapYear(year)) days++;
        year++;
      }
    }
  }

  return days;
}