type

     point=^node;

     node=record

                g,w:longint;

                next,anti:point;

     end;

 var

    i,j,k,l,m,n,ans,s,t:longint;

    a:array[..] of point;

    d,dv:array[..] of longint;

    c1,c2,c3:char;

 function min(x,y:longint):longint;inline;

          begin

               if x<y then min:=x else min:=y;

          end;

 procedure add(x,y,z:longint);inline;

           var p:point;

           begin

                new(p);p^.g:=y;p^.w:=z;p^.next:=a[x];a[x]:=p;

                new(p);p^.g:=x;p^.w:=;p^.next:=a[y];a[y]:=p;

                a[y]^.anti:=a[x];a[x]^.anti:=a[y];

           end;

 function dfs(x,flow:longint):longint;inline;

          var p:point;k:longint;

          begin

               if x=t then exit(flow);

               dfs:=;p:=a[x];

               while p<>nil do

                     begin

                          if (P^.w>) and (d[x]=(d[p^.g]+)) then

                             begin

                                  k:=dfs(p^.g,min(p^.w,flow-dfs));

                                  dec(p^.w,k);

                                  inc(p^.anti^.w,k);

                                  inc(dfs,k);

                                  if dfs=flow then exit;

                             end;

                          p:=p^.next;

                     end;

               if d[s]=n then exit;

               dec(dv[d[x]]);

               if dv[d[x]]= then d[s]:=n;

               inc(d[x]);

               inc(dv[d[x]]);

          end;

 function trans(x:char):longint;inline;

          begin

               case x of

                    'A'..'Z':exit(ord(x)-ord('A')+);

                    'a'..'z':exit(ord(x)-ord('a')+);

               end;

          end;

 function getc:longint;inline;

          begin

               repeat

                     read(c1);

               until (upcase(c1)>='A') and (upcase(c1)<='Z');

               exit(trans(c1));

          end;

 begin

      readln(m);n:=;

      for i:= to n do a[i]:=nil;

      s:=;t:=;

      for i:= to m do

          begin

               j:=getc;k:=getc;readln(l);

               add(j,k,l);

          end;

      fillchar(d,sizeof(d),);

      fillchar(dv,sizeof(dv),);

      dv[]:=n;

      ans:=;

      while d[s]<n do inc(ans,dfs(s,maxlongint));

      writeln(ans);

 end.