#include <stdio.h>

int main(int argc, char **argv) {
  int buf;
  int acc;
  int err;
  for(int i=1;i<argc;i++) {
    err=sscanf(argv[i], "%i", &buf);
    if(err!=1) {
      fprintf(stderr, "%s: arg #%d not an integer.\n",*argv,i);
      return 1;
    }
    acc+=buf;
  }
  acc/=argc-1;
  printf("%d\n",acc);
  return 0;
}