T=20;
n=[2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2];
a=[17,646,699,448,750,375,805,674,276,92,50,992,898,359,696,196,449,703,225,112,824,412,884,70,692,346,625,133,135,15,426,904,344,98,179,716,159,993,569,364];