Program to solve cyclobs' weird problem

cyclobs.cpp

#include <iostream>
#include <cstdlib>
using namespace std;

// Arbitrary precision c++ library
// compile with:
//  gcc thisfile.c -lgmp -lgmpxx -o mybinary
#include <gmpxx.h>

int main(int argc, char **argv){
    if (argc < 2) {
        cout << "Please give me a number!" << endl;
        cout << "Usage: " << argv[0] << " <number>" << endl;
        exit(1);
    }

    mpz_class num;

    try {
        num = argv[1];
    } catch (invalid_argument) {
        cout << "That wasn't a number dipshit" << endl;
        exit(1);
    }

    unsigned int i = 0;
    while (num != 1) {
        if (num % 1 == 0) {
            num /= 2;
        } else {
            num = num * 3 + 1;
        }
        i += 1;
    }
    cout << "Found 1 in " << i << " iterations." << endl;
}