var  
        c:array[1..10000] of longint;  
        n,i,k,s,d,a,b:longint;  
    begin  
    readln(n);  
    for i:=1 to n do begin readln(a,b); c[i]:=a+b; end;  
    i:=0;  
    k:=0;  
    s:=0;  
    repeat  
    inc(i);  
    d:=k+c[i]-8;  
    k:=d;  
    s:=s+d;  
    until i=n;  
    writeln(s);  
    end.  
总是80分，最后一个测试点215错误。。。求各位大神指导