next(1,2). next(2,3). next(3,4). next(4,5). next(5,6). next(6,7). next(7,8). next(8,9). next(9,10). next(10,11). next(11,12). next(12,13). next(13,14). next(14,15). next(15,16). next(16,17). next(17,18). next(18,19). next(19,20). next(20,21). next(21,22). next(17,23). next(23,24). next(24,25). next(25,26). next(26,27). next(27,28). next(23,29). next(29,30). next(30,31). next(31,32). next(32,33). next(33,34). next(34,35). next(35,36). next(36,37). next(32,38). next(38,39). next(39,40). next(40,41). next(41,42). doAt(startflow,3). doAt(a2,5). doAt(a13,6). doAt(a8,7). doAt(a24,8). doAt(a22,9). doAt(a10,10). doAt(a19,11). doAt(a18,12). doAt(a14,13). doAt(a1,14). doAt(a11,15). doAt(a6,16). doAt(a3,17). doAt(a9,18). doAt(a21,19). doAt(a4,20). doAt(endflow,21). doAt(a15,23). doAt(a17,24). doAt(a21,25). doAt(a4,26). doAt(endflow,27). doAt(a23,29). doAt(a12,30). doAt(a7,31). doAt(a25,32). doAt(a16,33). doAt(a21,34). doAt(a4,35). doAt(endflow,36). doAt(a5,38). doAt(a21,39). doAt(a4,40). doAt(endflow,41). compAt(a2,x13,4). leftrightnexts(33,38). leftrightnexts(24,29). leftrightnexts(18,23).