为什么不对呢?明明那么多人AC............
program rq343(input,output);
var a,b,i,n,m,t:integer;
s:array [1..1000] of boolean;
begin
readln(n,m);
t:=0;
for i:=1 to 1000 do
s[i]:=false;
for i:=1 to m do
begin
readln(a,b);
if not s[a] then begin inc(t);
s[a]:=true;
end;
if not s[b] then begin inc(t);
s[b]:=true;
end;
end;
write(t);
end.