void save_img() {
    FILE* si = fopen("1.png","wb");
    png_structp sips = png_create_write_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);
    png_infop sipi = png_create_info_struct(sips);
    png_init_io (sips,si);
    png_set_IHDR(sips,sipi,holst_x,holst_y,8,PNG_COLOR_TYPE_RGB,PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);

    u8* rows[holst_y];

    u64 do1 = 3*okno_x*((okno_y - holst_y)/2);
    u64 do2 = 3*((okno_x - holst_x)/2);
    u8 dob = (okno_x - holst_x)%2;

    okno_num = okno + do1 + do2;

    holst = malloc(holst_x*holst_y*3);

    i2 = 0;
    while (i2 < holst_y) {
        i = 0;
        rows[holst_y - i2 - 1] = holst + (i2*holst_x*3);
        while (i < holst_x) {
            *(holst + i*i2*3 - 1) = *okno_num;
            okno_num++;
            *(holst + i*i2*3) = *okno_num;
            okno_num++;
            *(holst + i*i2*3 + 1) = *okno_num;
            okno_num++;

            okno_num = okno_num + do2*2 + dob;

            i++;
        }
    }

    free(holst);

    png_set_rows(si,sipi,rows);
    png_write_png(si,sipi,PNG_TRANSFORM_IDENTITY,NULL);
    png_write_end(si,sipi);
    png_destroy_write_struct(&si,NULL);
    fclose(si);
}