Calculate how many days are before the founding of new China

Enter a date from the keyboard in the format of ymd.

It is required to calculate the number of days between this date and October 1, 1949.

E.g:

User input: 1949-10-2
Program output: 1

User input: 1949-11-1
program output: 31

Input format

Enter the year, month, and date. Every two numbers are separated by a-to ensure that the data is legal.

Output format

A number indicates how many days are this date from the founding day of New China.

#include<stdio.h>
int main()
{
    
    
	int y,m,d,day,d1=0,d2=0,d3=0,x;
	scanf("%d-%d-%d",&y,&m,&d);
	x=y-1949;
	if(x>0)
	{
    
    
		switch(m-1)
		{
    
    
			case 11:d1+=30;
			case 10:d1+=31;
			case 9:d1+=30;
			case 8:d1+=31;
			case 7:d1+=31;
			case 6:d1+=30;
			case 5:d1+=31;
			case 4:d1+=30;
			case 3:d1+=31;
			case 2:d1+=28;
			case 1:d1+=31;break;
		}
		if(m>2&&y%4==0&&y%100!=0||y%400==0)
			d1++;
		d2=(x-1)*365;
		if(x/4>1)
			d2+=x/4;
		d3=91;
		day=d1+d2+d3+d;
	}
	else
	{
    
    
		if(m-10>0)
		{
    
    
			switch(m-1)
			{
    
    
				case 11:d1+=60;break;
				case 10:d1+=30;break;
			}
			day=d1+d;
		}
		else
			day=d-1;
	}
	printf("%d\n",day);
}