C++ time until Christmas in progress

#include <iostream>
#include <time.h>
using namespace std;

int main() {

clock_t start = clock();
tm* my_time;
time_t t = time(NULL);


char* charTime = ctime(&t);
cout << charTime;
my_time = localtime(&t);
int day = my_time->tm_mday;
int month = my_time->tm_mon + 1;
int year = my_time->tm_year + 1900;

int chm = 12;
int chd = 25;

int tmtd = 0;
int tmtm = 0;

int jan = 31;
int feb = 28;
int mar = 31;
int apr = 30;
int may = 31;
int jun = 30;
int jul = 31;
int aug = 31;
int sep = 30;
int oct = 31;
int nov = 30;
int dec = 31;

int mdays = 0;
if (month == chm) {
    if (day == chd) {
        cout << "It is christmas!";
    }
    else if (day != chd && day < 25) {
        tmtd = chd - day;
        cout << "There are " << tmtd << " days until Christmas";
    }
    else if (day != chd && day > 25) {
        tmtd = 365 - (30 - day);
        cout << "There are " << tmtd << " days until Christmas";
    }
    else {
        cout << "Error";
    }
}

else if (month != chm) {
    tmtm = chm - month;

    if (month == 1) {
        mdays = jan;
        tmtd = mdays - 5;
        cout << "There are 11 months and " << mdays << " days until Christmas";
    }
}


}