＜C＞. Calculation date to day conversion

#include<stdio.h>
int runyearpanduan(int x)
{
    if ((x % 4 == 0 && x % 100 != 0) || (x % 400 == 0))
    {
        return 1; // Leap year 
    }
    else
    {
        return 0;// Ordinary year 
    }
}
int main()
{
    int year = 0;
    int month = 0;
    int days = 0;
    int i = 0;
    scanf("%d %d %d", &year,&month,&days);
    int runyear = 0;
    runyear = runyearpanduan(year);
    int run[12] = { 31,29,31,30,31,30,31,31,30,31,30,31 };
    int ping[12] = { 31,28,31,30,31,30,31,31,30,31,30,31 };
    int sum = 0;
    if (runyear == 1)
    {
        for (i = 0; i < month - 1; i++)
        {
            sum = sum + run[i];
        }
        sum = sum + days;
        printf("%d", sum);
    }
    if (runyear == 0)
    {
        for (i = 0; i < month - 1; i++)
        {
            sum = sum + ping[i];
        }
        sum = sum + days;
        printf("%d", sum);
    }
    return 0;
}

// Seamless switching of English Pinyin , Ha ha ha ha ha ha ha