if condition not executing for big numbers.why? whats wrong in the code?

for(int i=0;i<=f;i++)
	
{
    BigInteger ib=BigInteger.valueOf((long)i);
    //BigInteger r=  g1.Power(i);
    //System.out.println("g^ib =" +r);
    BigInteger s= g1.modPow(ib,p1);
    //System.out.println("r:" +r);

    //System.out.println("a" +a1);
    //System.out.println("p" +p1);
    //System.out.println("s:" +s);
    //System.out.println("a1:" +a1);
    //BigInteger a1 = BigInteger.valueOf((long)a);

    if(s.equals(a1))
    {
        System.out.println("The value of m is : \t" +i);
    }
    break;
}
//else
// System.out.print("the value did not match \n");

}