HDU 5478 Can you find it(数学问题)

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
typedef long long LL;
const LL INF = 0xffffff;
const LL maxn = 100005;
const LL MOD = 1e9+7;
LL C, k1, k2, b1;

LL QuickPow(LL a, LL k, LL mod)
{
    LL ans = 1, P = a;
    while( k )
    {
        if(k%2 == 1)
            ans = (ans * P)%mod;
        k /= 2;
        P = (P * P)%mod;
    }
    return ans;
}

int main()
{
    LL ans = 0, a, b;
    int cas = 1;

    while(cin >> C >> k1 >> b1 >> k2)
    {
        ans = 0;
        printf("Case #%d:\n", cas ++);

        for(int i=1; i<C; i++)///枚举a
        {
            a = i;
            b = C - QuickPow(a, k1+b1, C);
            if( (QuickPow(a, 2*k1+b1, C) + QuickPow(b, k2+1, C))%C == 0 )
            {
                printf("%I64d %I64d\n", a, b);
                ans ++;
            }

        }
        if(ans == 0)
            printf("-1\n");
    }
    return 0;
}