usaco 3.2 fact4 2008.7.18

来源：互联网发布：jpeg量化矩阵编辑：程序博客网时间：2024/05/21 19:33

usaco 3.2 fact4 2008.7.18

{

ID:

PROG: fact4

LANG: PASCAL

}

program p_fact4;const fin='fact4.in';fout='fact4.out';var n,sum,p,i,nn,n2,n5:longint;      f1,f2:text;begin     assign(f1,fin);reset(f1);assign(f2,fout);rewrite(f2);     sum:=1;read(f1,n);     if n<=10 then begin                         for i:=2 to n do                           sum:=sum*i;                        while sum mod 10=0 do sum:=sum div 10;                        sum:=sum mod 10;                          end                          else                          begin                           nn:=0;                            for i:=5 to n do                              begin                                 p:=i;                                 while(p mod 5=0) do begin inc(nn);p:=p div 5;end;                              end;                            n2:=0;n5:=0;                            for i:=2 to n do                               begin                                 p:=i;                                 while (p mod 2=0)and(n2<>nn)do begin inc(n2);p:=p div 2;end;                                 while (p mod 5=0)and(n5<>nn)do begin inc(n5);p:=p div 5;end;                                 sum:=(sum*p) mod 10;                               end;                          end;    writeln(f2,sum);    close(f1);    close(f2);    end.

0 0