Program to read in primes from a text file and perform the "switch flipping" problem

switches.c

#include <stdio.h>
#include <stdlib.h>
#define N 10

int switches[N];

void flipSwitches(int p) {
        int j;
        int flipped = 0;
        for (j = 1; j <= N; j++) {
            if (j % p == 0){
                if (switches[j] == 0) {
                     switches[j] = 1;
                }
                else if (switches[j] == 1){
                    switches[j] = 0;
                }
            }
        }
    }
                        
void main() {
        int q;
        int w;
        
        for (q = 0; q < N; q++){
                switches[q] = 1;
        }
        FILE* f = fopen("primes.txt", "r");
        int prime = 0;
        while( fscanf(f, "%d,", &prime) > 0) {
            flipSwitches(prime);
        }
        fclose(f);
        long num = 0;
        for (w = 0; w < N; w++){
                if (switches[w] == 1){
                        num = num + 1;
                }
        }
        printf("Number of flipped switches is %ld\n", num); 
}