A.cpp

#include<iostream>

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

intdaysInMonth(int year, int month) {
constint daysInMonth[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
return daysInMonth[month];
}

intmain() {
int year1, month1, day1, hour1, min1, sec1;
int year2, month2, day2, hour2, min2, sec2;

 std::cin >> year1 >> month1 >> day1 >> hour1 >> min1 >> sec1;
 std::cin >> year2 >> month2 >> day2 >> hour2 >> min2 >> sec2;

longlong fullDays = 0;
longlong remainingSeconds = 0;

while (year1 != year2 || month1 != month2 || day1 != day2) {
 remainingSeconds += 24ll * 60 * 60;
 day1++;

if (day1 > daysInMonth(year1, month1)) {
 day1 = 1;
 month1++;

if (month1 > 12) {
 month1 = 1;
 year1++;
 }
 }

if (day1 > daysInMonth(year1, month1)) {
 day1 = 1;
 month1++;

if (month1 > 12) {
 month1 = 1;
 year1++;
 }
 }
 }

 remainingSeconds += (hour2 - hour1) * 3600 + (min2 - min1) * 60 + (sec2 - sec1);
 fullDays = remainingSeconds / (24 * 60 * 60);
 remainingSeconds %= (24 * 60 * 60);

 std::cout << fullDays << "" << remainingSeconds << std::endl;

return0;
}