输入7得不出616

#include<iostream>

int main() {
	long long k_molecule,k_denominator=1;
	long long n_molecule = 1, n_denominator = 1;
	long long temp;
	do {
		std::cin >> k_molecule; 
	} while (k_molecule <= 0);

	while (k_molecule* n_denominator - k_denominator >= 0){
		k_molecule *= n_denominator;
		temp = k_denominator;
		k_denominator *= n_denominator;
		k_molecule -= temp;
		++n_denominator;
	} 
	std::cout << n_denominator;
}