#pragma GCC optimize ( "O3" )
#pragma GCC optimize( "unroll-loops" )
#pragma GCC target ( "sse4.2,fma,avx2,popcnt,lzcnt,bmi2" )
#include <iostream>
#include <string>
#include <stdio.h>
#include <stdint.h>
#include <cassert>
using namespace std;

using ll = long long;

#define MAIN main
#define TYPE_OF( VAR ) remove_const<remove_reference<decltype( VAR )>::type >::type
#define UNTIE ios_base::sync_with_stdio( false ); cin.tie( nullptr )
#define CEXPR( LL , BOUND , VALUE ) constexpr const LL BOUND = VALUE
#define CIN( LL , A ) LL A; cin >> A
#define ASSERT( A , MIN , MAX ) assert( ( MIN ) <= A && A <= ( MAX ) )
#define CIN_ASSERT( A , MIN , MAX ) CIN( TYPE_OF( MAX ) , A ); ASSERT( A , MIN , MAX )
#define FOR( VAR , INITIAL , FINAL_PLUS_ONE ) for( TYPE_OF( FINAL_PLUS_ONE ) VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ )
#define REPEAT( HOW_MANY_TIMES ) FOR( VARIABLE_FOR_REPEAT ## HOW_MANY_TIMES , 0 , HOW_MANY_TIMES )
#define QUIT return 0
#define COUT( ANSWER ) cout << ( ANSWER ) << "\n"
#define RETURN( ANSWER ) COUT( ANSWER ); QUIT

#define POWER_MOD( ANSWER , ARGUMENT , EXPONENT , MODULO )		\
  ll ANSWER{ 1 };					\
  {									\
    ll ARGUMENT_FOR_SQUARE_FOR_POWER = ( MODULO + ( ( ARGUMENT ) % MODULO ) ) % MODULO; \
    TYPE_OF( EXPONENT ) EXPONENT_FOR_SQUARE_FOR_POWER = ( EXPONENT );	\
    while( EXPONENT_FOR_SQUARE_FOR_POWER != 0 ){			\
      if( EXPONENT_FOR_SQUARE_FOR_POWER % 2 == 1 ){			\
	ANSWER = ( ANSWER * ARGUMENT_FOR_SQUARE_FOR_POWER ) % MODULO;	\
      }									\
      ARGUMENT_FOR_SQUARE_FOR_POWER = ( ARGUMENT_FOR_SQUARE_FOR_POWER * ARGUMENT_FOR_SQUARE_FOR_POWER ) % MODULO; \
      EXPONENT_FOR_SQUARE_FOR_POWER /= 2;				\
    }									\
  }									\

int MAIN()
{
  UNTIE;
  CEXPR( ll , bound_T , 100000 );
  CIN_ASSERT( T , 1 , bound_T );
  CEXPR( ll , bound_NM , 1000000000000000000 );
  CEXPR( ll , mod_max , 1000000000 );
  CEXPR( int , exponent , 400000000 - 1 );
  constexpr ll p[2] = { 2 , 5 };
  REPEAT( T ){
    CIN_ASSERT( N , 1 , bound_NM );
    CIN_ASSERT( M , 1 , bound_NM );
    ll mod = mod_max;
    bool solvable = true;
    FOR( i , 0 , 2 ){
      const ll& pi = p[i];
      REPEAT( 9 ){
	if( N % pi == 0 ){
	  if( M % pi == 0 ){
	    N /= pi;
	    M /= pi;
	    mod /= pi;
	  } else {
	    solvable = false;
	    break;
	  }
	} else {
	  break;
	}
      }
      if( ! solvable ){
	break;
      }
    }
    if( solvable ){
      POWER_MOD( inv_N , N , exponent , mod );
      ll n = ( inv_N * ( mod - ( M % mod ) ) ) % mod;
      if( n == 0 ){
	n = mod;
      }
      COUT( n );
    } else {
      COUT( -1 );
    }
  }
  QUIT;
}