TRAM195 PASCAL

var     n:longint;
        a,b:array[1..1000000] of longint;

procedure nhap;
var i:longint;
begin
    readln(n);
    for i:=1 to n do
        readln(a[i],b[i]);
end;

procedure giai;
var i,maxx,s:longint;
begin
    maxx:=0;s:=0;
    for i:=1 to n do
    begin
           s:=s-a[i]+b[i];
        if s>maxx then maxx:=s;
    end;
    write(maxx);
end;

begin
    assign(input, 'tram195.inp');reset(input);
    assign(output, 'tram195.out');rewrite(output);
    nhap;
    giai;
end.