问使用GMP库运行C++程序会导致错误: C4146:一元减号运算符应用于无符号类型，结果仍未签名

EN

#include <gmp.h>
int main() {
    gmp_randstate_t state;  // variable state for gmp_randinit, must be initialized 
    mpz_t p, q, N;
    mp_bitcnt_t n;  // number of bits for the number in range 0 to (2^n)-1, inclusive.

    n = 10;
    gmp_randinit_default(state);    // Initialize state with a default algorithm.

    while (true)
    {
        mpz_urandomb(p, state, n);  // Generate a uniformly distributed random integer
        if (mpz_probab_prime_p(p, 50) == 2) // Determine whether p is prime. Return 2 if p is definitely prime
            break;
    }
    while (true)
    {
        mpz_urandomb(q, state, n);  // Generate a uniformly distributed random integer
        if (mpz_probab_prime_p(q, 50) == 2) // Determine whether q is prime. Return 2 if q is definitely prime
            break;
    }

    return 0;
}

C4146: unary minus operator applied to unsigned type, result still unsigned