solution: |
  "1.Qb6-b5 ! threat:
            2.Bf3-g4 + 
                2...Kf5*e4 
                    3.Qb5-d3 # 
        1...c5-c4 
            2.Sg8*e7 + 
                2...Sd5*e7 
                    3.Re4-f4 # 
                2...Sc6*e7 
                    3.Qb5*d7 # 
        1...Sd5-f4 
            2.Se2-d4 + 
                2...c5*d4 
                    3.Re4*f4 # 
                2...e5*d4 
                    3.Rg6-g5 # 
                2...Sc6*d4 
                    3.Sg8*e7 # 
        1...Sd5-f6 
            2.Qb5-c4 threat:
                    3.Rg6-g5 # 
                2...Sf6-d5 
                    3.Bf3-g4 # 
                2...Sf6*e4 
                    3.Qc4*e4 # 
                    3.Bf3-g4 # 
                    3.Bf3*e4 # 
                2...Sf6-h7 
                    3.Bf3-g4 # 
                2...Sf6*g8 
                    3.Bf3-g4 # 
                2...g7*h6 
                    3.Sg8*h6 #"
  "1... c4 2. Sd4+
    2... S:d4, e:d4 3. Rg5#
  1... Sf4 2. S:e7+
    2... S:e7 3. Rg5#
  
  1. Qb5! [2. Bg4+
    2... K:e4 3. Qd3#]
  1... c4 2. S:e7+
    2... Sc:e7 3. Q:d7#
    2... Sd:e7 3. Rf4#
  1... Sf4 2. Sd4+
    2... S:d4 3. S:e7#
    2... c:d4 3. R:f4#
  1... Sf6 2. Qc4 [3. Rg5#]
    2... g:h6 3. S:h6#
    2... S:g8 3. Bg4#"
keywords: 
  - Reciprocal