HELP!!!!

Written in C

#include

#include

#include

#include

int main(int argc, char* argv[]) {

int num;

int num_set = 0;

int len;

int opt;

while ((opt = getopt(argc, argv, "vn:o:")) >= 0) {

switch (opt) {

case 'v': printf("316"); break;

case 'n': num_set = 1; num = atoi(optarg); printf("%i", num); break;

case 'o': len = strlen(optarg); printf("%i", len); break;

}

}

if (!num_set) { printf("0"); exit(1); }

return 0;

}

Given the code above, what's the output if we run the program prog with the commend "./prog -vn 8"