25 lines
560 B
ObjectPascal

program star;
var i,j,k,n,max:longint;
f:array[0..2000]of longint;
a,b,c:array[1..1000]of longint;
begin
assign(input,'hunger.in'); reset(input);
assign(output,'hunger.out');rewrite(output);
readln(n);
for i:=1 to n do
begin
readln(a[i],b[i]);
c[i]:=b[i]-a[i]+1;
if b[i]>max then max:=b[i];
end;
for i:=1 to max do
begin
f[i]:=f[i-1];
for j:=1 to n do
if b[j]=i then
if f[a[j]-1]+c[j]>f[i] then f[i]:=f[a[j]-1]+c[j];
end;
writeln(f[max]);
close(input); close(output);
end.