2005noip解题报告
program tree;
uses crt;
var
fi,fo:text;
long,m,total:word;
a,b:array[1..100] of word;
i,jian:integer;
all:array[0..10000] of 0..1;
begin
clrscr;
total:=0;
for i:=0 to 10000 do
all[i]:=1;
assign(fi,'tree.in');
reset(fi);
read(fi,long);
read(fi,m);
readln(fi);
for i:=1 to m do
begin
read(fi,a[i]);
read(fi,b[i]);
readln(fi);
end;
for i:=1 to m do
begin
for jian:=a[i] to b[i] do
begin
all[jian]:=0;
end;
end;
for i:=0 to long do
begin
if all[i]=1 then
inc(total);
end;
assign(fo,'tree.out');
rewrite(fo);
writeln(fo,total);
close(fi);
close(fo);
end.