Thread: Please help me (C Programming)

here's the code of the program, the problem is stated in the bottom.

Code:

#include <stdio.h>
#define SIZE 10
int SeatDis(int[], int);
main() {
    static int Ar[SIZE] = { 0 };
    int a, ok;
        puts("Enter 1 for "First class"");
        puts("Enter 2 for "Econom class"");
        puts("Enter 3 to Quit");
            scanf_s("%d", &a);


            if (a == 1 || a == 2) {
                ok = SeatDis(Ar, (a - 1) * 5);
                if (ok != 0){
                    printf("Your seat num is %d\n", ok);
                    main();
            }
                    if (a == 1 && SeatDis(Ar, 5)) {
                        printf("No seats found in First Class\n");
                        printf("Wish to buy a seat in Econom class?(1 or Other = Yes : 0 = No)\n");
                        scanf_s("%d", &a);
                        if (a) {
                            printf("Your seat num is %d\n", SeatDis(Ar, 5));
                            main();
                        }
                    }
                    else {
                        if (a == 2 && SeatDis(Ar, 0)) {
                            printf("No seats found in Econom Class\n");
                            printf("Wish to buy a seat in First class?(1 = Yes : 2 = No)\n");
                            scanf_s("%d", &a);
                            if (a) {
                                printf("Your seat num is %d\n", SeatDis(Ar, 0));
                                main();
                            }
                        }


                        else printf("Next flight in three hours time from now...\n");
                    }
                }
        else {
            if (a != 3) {
                printf("Something went wrong...\n");
                main();
            }
        }
    system("pause");
    return 0;
    }


int SeatDis(int Ar[], int c) {
    for (int b = c + 5; c < b; c++) {
        if (Ar[c] == 0) {
            Ar[c] = 1;
            return c + 1;
        }
    }
    return 0;
}

The program asks you If you would like to buy a seat in the plane. Depending on your decision and amount of spare seats it reacts..
In the plane first (1-5) seats are First class, 6-10 are Econom.
The program works fine except of one bug that I can't figure out how to solve.
When all of the seats in one class are taken It asks me if I want to change my class - I answer: 1 meaning ok, but instead of giving me the seat from start (1-5 or 6-10) It gives me 2-10 or 7-10 seats, meaning that one seat had been lost, because no one had bought it.