这个会报错怎么办 他说快速幂那里complex不是个类型怎么办

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

int c, K;

int II;

struct complex {
	int real, imag;
	complex(int real = 0, int imag = 0):real(real), imag(imag){}
	bool operator == (complex y) {
		return real == y.real and imag == y.imag;
	}
	complex operator * (complex y) {
		return complex(real * y.real % K + II * imag * y.imag % K % K, (imag*y.real%K+real*y.imag%K) % K);
	}
};

complex Pow(complex idx, int P) {
	if(P == 0) return {1, 0};
	if(P == 1) return idx;
	int u = Pow(idx, P/2);
	if(P&1) return u*u*idx;
	else return u*u; 
}

bool check(complex idx) {
	if(Pow(idx, (K-1)/2) == 1) {
		return true;
	} else {
		return false;
	}
}

signed main() {
	ios::sync_with_stdio(0); cin.tie(0);
	int t; cin >> t;
	while(t--) {
		cin >> c >> K;
		int a = rand()%K;
		while(check(a)) {
			a = rand()%K;
		} 
		II = (a*a-c+K) % K;
		int x0 = int(Pow(complex(a,1), (mod+1)>>1).real);
		int x1 = (K-x0) % K;
		if(x0 == x1) cout << x1 << endl;
		else cout << x0 << " " << x1 << endl;
	}
	
	return 0;
}