for (int i = start; i < argc; i++) {
fin.open(argv[i]);
if (!fin.is_open()) { fprintf(stderr, "Cannot open %s! It may not exist.\n", argv[i]); exit(-1); }
for (int i = start; i < argc; i++) {
fin.open(argv[i]);
if (!fin.is_open()) { fprintf(stderr, "Cannot open %s! It may not exist.\n", argv[i]); exit(-1); }