for how many unique pairs of nonnegative integers { a , b } is the equation a ^ 2 - b ^ 2 = 220 true ?
"answer d ( a + b ) ( a - b ) = 220 6 cases for ( a + b ) , ( a - b ) 220 , 1 110 , 2 55 , 4 44,5 22 , 10 20,11 answer d"
divide(log(220), log(add(const_4, const_1)))