Standard input is empty
case n of 0: a := '1'; 1: a := '1'; 2: a := '2'; 3: a := '6'; 4: a := '24'; 5: a := '120'; 6: a := '720'; 7: a := '5040'; 8: a := '40320'; 9: a := '362880'; 10: a := '3628800'; 11: a := '39916800'; 12: a := '479001600'; 13: a := '6227020800'; 14: a := '87178291200'; 15: a := '1307674368000'; 16: a := '20922789888000'; 17: a := '355687428096000'; 18: a := '6402373705728000'; 19: a := '121645100408832000'; 20: a := '2432902008176640000'; 21: a := '51090942171709440000'; 22: a := '1124000727777607680000'; 23: a := '25852016738884976640000'; 24: a := '620448401733239439360000'; 25: a := '15511210043330985984000000'; 26: a := '403291461126605635584000000'; 27: a := '10888869450418352160768000000'; 28: a := '304888344611713860501504000000'; 29: a := '8841761993739701954543616000000'; 30: a := '265252859812191058636308480000000'; 31: a := '8222838654177922817725562880000000'; 32: a := '263130836933693530167218012160000000'; 33: a := '8683317618811886495518194401280000000'; 34: a := '295232799039604140847618609643520000000'; 35: a := '10333147966386144929666651337523200000000'; 36: a := '371993326789901217467999448150835200000000'; 37: a := '13763753091226345046315979581580902400000000'; 38: a := '523022617466601111760007224100074291200000000'; 39: a := '20397882081197443358640281739902897356800000000'; 40: a := '815915283247897734345611269596115894272000000000'; 41: a := '33452526613163807108170062053440751665152000000000'; 42: a := '1405006117752879898543142606244511569936384000000000'; 43: a := '60415263063373835637355132068513997507264512000000000'; 44: a := '2658271574788448768043625811014615890319638528000000000'; 45: a := '119622220865480194561963161495657715064383733760000000000'; 46: a := '5502622159812088949850305428800254892961651752960000000000'; 47: a := '258623241511168180642964355153611979969197632389120000000000'; 48: a := '12413915592536072670862289047373375038521486354677760000000000'; 49: a := '608281864034267560872252163321295376887552831379210240000000000'; 50: a := '30414093201713378043612608166064768844377641568960512000000000000'; 51: a := '1551118753287382280224243016469303211063259720016986112000000000000'; 52: a := '80658175170943878571660636856403766975289505440883277824000000000000'; 53: a := '4274883284060025564298013753389399649690343788366813724672000000000000'; 54: a := '230843697339241380472092742683027581083278564571807941132288000000000000'; 55: a := '12696403353658275925965100847566516959580321051449436762275840000000000000'; 56: a := '710998587804863451854045647463724949736497978881168458687447040000000000000'; 57: a := '40526919504877216755680601905432322134980384796226602145184481280000000000000'; 58: a := '2350561331282878571829474910515074683828862318181142924420699914240000000000000'; 59: a := '138683118545689835737939019720389406345902876772687432540821294940160000000000000'; 60: a := '8320987112741390144276341183223364380754172606361245952449277696409600000000000000'; 61: a := '507580213877224798800856812176625227226004528988036003099405939480985600000000000000'; 62: a := '31469973260387937525653122354950764088012280797258232192163168247821107200000000000000'; 63: a := '1982608315404440064116146708361898137544773690227268628106279599612729753600000000000000'; 64: a := '126886932185884164103433389335161480802865516174545192198801894375214704230400000000000000'; end