// the function returns the multiply of p1 and p2 big
function mul_b(p1, p2) {
    var eql = ""; // fine value
    var r_eql = ""; // reversed value retured
    var carry = 0;
    var length_p1 = p1.length - 1;
    console.log( "length first number " + length_p1);
    var length_p2 = p2.length - 1;
    console.log( "length secnd number " + length_p2);
    if (length_p1 != length_p2){// eql two number by padding zeros
        return "Please make both sides equal!";
    }
    console.log(length_p1 + "=" + length_p2);
    var A1,A2;
    var A3 = 0;
    for(var j = length_p1; j>=0; j--){
        var k = j;
        A3 = 0;
        for( var i = length_p1 ; i >= j ; i-- ){
            A1 = parseInt(p1.charAt(k));
            A2 = parseInt(p2.charAt(i));
            k+=1;
            console.log("("+A1+","+A2+")");
            A3 = (A1 * A2) + A3;
            console.log("("+A3+")");
        }
        eql = A3.toString().concat(eql);
        console.log("("+eql+")");
    }
    for(var j = (length_p1-1); j>=0; j--){
        var k = j;
        A3 = 0;
        for( var i = 0; i<=j; i++ ){
            A1 = parseInt(p1.charAt(k));
            A2 = parseInt(p2.charAt(i));
            k-=1;
            console.log("("+A1+","+A2+") " + k + " , "+ i);
            A3 = (A1 * A2)+A3;
            console.log("("+A3+")");
        }
        eql = A3.toString().concat(eql);
        console.log("("+eql+")");
    }
    var f_eql = "";
    f_eql = eql.charAt(0);
    for (var i = 1; i<=(eql.length); i++){
        if (eql.charAt(i+1) == ""){
            f_eql += (parseInt(eql.charAt(i)) + carry + 0).toString();
        }else{
            if ((parseInt(eql.charAt(i)) + parseInt(eql.charAt(i+1)) + carry)<10){//carry
                f_eql += (parseInt(eql.charAt(i)) + parseInt(eql.charAt(i+1))+ carry).toString();
                carry = 0;
            } else {
                f_eql += (parseInt(eql.charAt(i)) + parseInt(eql.charAt(i+1)) - 10).toString();
                carry = 1;
            }
        }
        console.log("("+eql.charAt(i)+")"+eql.charAt(i+1));
        i += 1;
    }
    console.log("fine = ("+eql+")");
    console.log("("+f_eql+")");
    return   f_eql;
}