c语言，不会写，好心人们帮帮忙

#include<stdio.h>
int D[13];
bool check(int y)
{
    if(y % 400 == 0 || (y % 4 == 0 && y % 100 != 0))
        return true;
    return false;
}
int main()
{
    D[1] = 31 , D[2] = 28 , D[3] = 31 , D[4] = 30 , D[5] = 31 , D[6] = 30;
    D[7] = 31 , D[8] = 31 , D[9] = 30 , D[10] = 31 , D[11] = 30 , D[12] = 31;
    int ans=0;
    for(int y=2002;y<=2021;y++)
    {
        if(check(y)) 
            D[2] = 29;
        else
            D[2] = 28;
        for(int m=(y==2002?10:1) ; m <= (y == 2021 ? 10 : 12) ;m++)
        {
            if(y == 2021 && m == 10)
                D[m] = 24;
            for(int d=(y==2002&&m==10?24:1);d <=D[m];d++)
                ans++;
        }
    }
    printf("%d\n",ans);
    return 0;
}

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