var

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

    a:array[..,..] of longint;

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

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

          begin

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

          end;

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

          var i,j,k,l:longint;

          begin

               if x=t then exit(flow);

               dfs:=;

               for i:= to n do

                   if (a[x,i]>) and (d[x]=(d[i]+)) then

                      begin

                           k:=dfs(i,min(flow-dfs,a[x,i]));

                           dec(a[x,i],k);

                           inc(a[i,x],k);

                           inc(dfs,k);

                           if dfs=flow then exit;

                      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;

 begin

      readln(n,m,s,t);

      fillchar(a,sizeof(a),);

      for i:= to m do

          begin

               readln(j,k,l);

               inc(a[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.