太酷了？

#include <bits/stdc++.h>
using namespace std;

long long su(long long a) {
	for (int i = 2; i * i <= a; i++) {
		if (a % i == 0) {
			return 0;
		}
	}
	return 1;
}

int main() {
	long long a[50001], b[50001], g = 0, n, ans;
	cin >> n;
	a[0] = 1;
	a[1] = 1;
	for (int i = 2; i <= 50; i++) {
		a[i] = a[i - 1] + a[i - 2] % int(pow(2, 31));
	}
	for (int i = 2; i <= 500000; i++) {
		if (su(i)) {
			b[g] = i;
			g++;
		}
	}
	cout << a[n - 1] << "=";
	ans = a[n - 1];
	if (su(ans)) {
		cout << ans;
		return 0;
	}
	for (long long i = 0; b[i] <= ans; i++) {
		if (ans % b[i] == 0) {
			if (su(ans / b[i])) {
				cout << b[i] << "*" << ans / b[i];
				return 0;
			}
		}
	}
	for (long long i = 0; b[i] <= ans; i++) {
		for (long long j = 0; b[j]*b[i] <= ans; i++) {
			if (ans % b[i] == 0 && ans % b[j] == 0 && ans % b[i] % b[j] == 0) {
				if (su(ans / b[i] / b[j])) {
					cout << b[i] << "*" <<  b[j] << "*" << ans / b[i] / b[j];
					return 0;
				}
			}
		}
	}
	return 0;
}