( {250 \choose 2} \cdot {248 \choose 2} \cdot ... \cdot {212 \choose 2} - {150 \choose 2} \cdot {148 \choose 2} \cdot ... \cdot {112 \choose 2} - {100 \choose 2} \cdot {98 \choose 2} \cdot ... \cdot {62 \choose 2} ) / 20!