/TAOQUAN - Táo quân

              Uses Crt;
        Var n,m,k,i,d,sn,pt,e:longint;
        Begin
            readln(n,m,k);
            if m*2<=n then begin sn:=m; pt:=n-m*2; end
             else if n div 2<=m then begin
                  sn:=n div 2;
                  pt:=n-2*(n div 2)+(m-(n div 2));
              end;
            //writeln(sn);
            if pt>=k then e:=0 else
            begin
             e:=(k-pt) div 3;
             if (k-pt) mod 3<>0 then e:=e+1;
            end;
            //writeln(e);
            sn:=sn-e;
            writeln(sn);
            readln;
        End.