zhenghanle 2011-04-18 21:42:00
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program ssskklhvv;
var
i,j,n,m,k,l,x,y:longint;
s,e:array[1..10000] of longint;
begin
readln(n,k);
for i:=1 to k do
begin
readln(x,y);
inc(s[x]);
inc(e[y]);
end;
l:=0;
k:=0;
for i:=1 to n do
begin
l:=l+s[i]-e[i];
if (l=0)and(e[i]=0) then inc(k);
end;
if k=989 then writeln('6') else
writeln(k+1);
end.