poj1808--二次剩余

#include<stdio.h>
#define LL long long

LL pow_mod(LL a, LL n, LL mod) {
LL res = 1;
while(n) {
if (n & 1) res = res * a % mod;
n >>= 1;
a = a * a % mod;
}
return res;
}

LL modsqr(LL a, LL n){
LL b,k,i,x;
a = (a % n + n) % n;
if(pow_mod(a, (n-1) / 2, n) == 1){
return 1;
}
return -1;
}

int main ()
{
int T,cas=1;
scanf("%d",&T);
while(T--)
{
LL a,b;
scanf("%I64d%I64d",&a,&b);
printf("Scenario #%d:\n%I64d\n\n",cas++,modsqr(a,b));
}
}