There are 89 students in a volunteer group for majors in math, statistics, or actuarial science. Thirteen students have a double-major in math and statistics. Twelve students have a double major in math and actuarial science. Thirteen students have a double major in statistics and actuarial science. There are 9 students doing a triple major. Thirty-nine students are majoring in at least statistics, and forty-four are majoring in at least actuarial science. How many students are majoring in at least mathematics?