#include <iostream>

bool mseek(int i, FILE* f) {
    int p = ftell(f);
    fseek(f, 0, SEEK_SET);
    int n = 0, c;
    while (!feof(f)) { fread(&c, sizeof(c), 1, f); if (c == i) n++; if (n > 2) break; }
    fseek(f, p, SEEK_SET);
    return n == 2;
}

int main(void)
{
    setlocale(LC_CTYPE, "Russian");
    using namespace std;
    FILE* fa;
    FILE* fb;
    int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 123, 24, 32 ,12 };
    int t[18], i, j = 0;
    fopen_s(&fa, "a.txt", "a+");
    fopen_s(&fb, "b.txt", "w+");
    if (fa == NULL)
    {
        perror("Oшибка открытия файла a.txt");
        return EXIT_FAILURE;
    }
    while (!feof)
    {
        for (int i = 0; i <= 18; i++)
        {
            fread(&t[i], sizeof(int), 1, fa);
            if (mseek(t[i], fa)) fwrite(&array[i], sizeof(int), 1, fb);
        }
    }
    fclose(fa);
    fclose(fb);
    system("pause");
}