Подсчет дней в году(структура) - выход из цикла while

#include <stdio.h>
#include <ctype.h>
#include <string.h>
int check(int,int,int);
struct month{
int num_Mon;
char name_MNTH[10];
char ABR[4];
int days;
};
    struct month MONTHS[12] = {
    {1,"January","JAN",31},
    {2,"February","FEB",28},
    {3,"March","MAR",31},
    {4,"April","APR",30},
    {5,"May","MAY",31},
    {6,"June","JUN",30},
    {7,"July","JUL",31},
    {8,"August","AUG",31},
    {9,"September","SEP",30},
    {10,"October","OCT",31},
    {11,"November","NOV",30},
    {12,"December","DEC",31},
};
int main(void)
{
    int input_day;
    int input_mon;
    int input_yar;
    int index;
    int total;
    int days_amount;
    printf("enter date for calculate(for example 01/12/1999):\n");
    while (scanf("%2d%*c%2d%*c%4d",&input_day,&input_mon,&input_yar) != 1)
    {
        if (input_yar % 4 == 0 )
            MONTHS[1].days = 29;
        else
            MONTHS[1].days = 28;
        days_amount = check(input_day,input_mon,input_yar);
                 printf("sum until %s - %d\n",MONTHS[input_mon - 1].name_MNTH,days_amount);
    }
return 0;
}
 
int check(int D,int M,int Y)
{
    int index;
    int total_mid = 0;
    int total;
    for (index =1;index < M;index++)
        total_mid+=MONTHS[index-1].days;
 
        total= total_mid+D;
 
 
            return total;
}

    days = 28+(!(y%4) && ((y%100) || !(y%400)));

while (scanf("%2d%*c%2d%*c%4d",&input_day,&input_mon,&input_yar) == 3)