For the C++ function below, please give the tightest asymptotic upper bound that can be determined for the function's runtime, assume that n>=1

int getValue(int n) {

int q = 0;

int p = 0;

for(int a = 1; a < n; a++) {

for(int b = a; b<16; b = b * 4) {

p++

}

q++

}

return p*q

}