Can please someone tell me as of why am I getting a WA in this question?
Can you please tell any corner case I might be missing?
import java.math.BigInteger;
import java.util.Scanner;
public class Main {
public static void main(String[] args)throws java.lang.Exception
{
Scanner S = new Scanner(System.in);
int T;
T = S.nextInt();
BigInteger A, B, N,MOD;
BigInteger one = BigInteger.valueOf(1);
for(int i = 0;i<T;i++)
{
A = S.nextBigInteger();
B = S.nextBigInteger();
N = S.nextBigInteger();
MOD = S.nextBigInteger();
if(N.compareTo(BigInteger.ZERO)==0)
{
BigInteger BO = BigInteger.ONE;
BO = BO.mod(MOD);
System.out.println(BO);
}
else if(N.compareTo(BigInteger.ONE)==0)//i.e. F = a + b
{
BigInteger ans = A.mod(MOD);
ans = ans.add(B.mod(MOD));
ans = ans.mod(MOD);
System.out.println(ans);
}
else
{
BigInteger AA = A;
AA = AA.subtract(one);//A = A - 1
BigInteger BA = B;//L = B
BigInteger BAAN = A.modPow(N, MOD);//A^N
BAAN = BAAN.subtract(one);//A^N - 1
BAAN = BAAN.mod(MOD);
BAAN = BAAN.multiply(BA);//A^N*B - B
BAAN = BAAN.divide(AA);//(A^N - 1)*B/(A-1)
BAAN = BAAN.mod(MOD);
BAAN = BAAN.add(A.modPow(N, MOD));
BAAN = BAAN.mod(MOD);
System.out.println(BAAN);
}
}
}
}
