Validating/Checking Date using C program

/*C program to validate date (Check date is valid or not).*/
 
#include <stdio.h>
 
int main()
{
    int dd,mm,yy;
     
    printf("Enter date (DD/MM/YYYY format): ");
    scanf("%d/%d/%d",&dd,&mm,&yy);
     
    //check year
    if(yy>=1900 && yy<=9999)
    {
        //check month
        if(mm>=1 && mm<=12)
        {
            //check days
            if((dd>=1 && dd<=31) && (mm==1 || mm==3 || mm==5 || mm==7 || mm==8 || mm==10 || mm==12))
                printf("Date is valid.\n");
            else if((dd>=1 && dd<=30) && (mm==4 || mm==6 || mm==9 || mm==11))
                printf("Date is valid.\n");
            else if((dd>=1 && dd<=28) && (mm==2))
                printf("Date is valid.\n");
            else if(dd==29 && mm==2 && (yy%400==0 ||(yy%4==0 && yy%100!=0)))
                printf("Date is valid.\n");
            else
                printf("Day is invalid.\n");
        }
        else
        {
            printf("Month is not valid.\n");
        }
    }
    else
    {
        printf("Year is not valid.\n");
    }
 
    return 0;    
}

Output

First Run:
Enter date (DD/MM/YYYY format): 17/03/1998
Date is valid.

Second Run:
Enter date (DD/MM/YYYY format): 29/02/2013
Day is invalid.