BZOJ 1096

const maxm=1e100;
      maxn=1000001;
var   f,x,p,c,sum,cost:array[0..maxn] of int64;
      q:array[0..maxn] of longint;
      n,i,h,t:longint; 

function calc(j,i:longint):int64;
begin
   calc:=cost[i]-cost[j]-sum[j]*(x[i]-x[j]);
end; 

function slope(j,k:longint):extended;
var tmp:int64;
begin
  tmp:=f[k]-f[j]-cost[k]+cost[j]+sum[k]*x[k]-sum[j]*x[j];
  if sum[k]=sum[j] then
   if tmp>=0 then exit(maxm)
    else exit(-maxm);
   slope:=tmp/(sum[k]-sum[j]);
end; 

begin
  readln(n);
  for i:=1 to n do readln(x[i],p[i],c[i]);
  for i:=1 to n do sum[i]:=sum[i-1]+p[i];
  for i:=1 to n do
     cost[i]:=cost[i-1]+sum[i-1]*(x[i]-x[i-1]);
  for i:=1 to n do
    begin
      while (h<t)and(slope(q[h],q[h+1])<x[i]) do inc(h);
      f[i]:=f[q[h]]+calc(q[h],i)+c[i];
      while (h<t)and(slope(q[t-1],q[t])>slope(q[t],i)) do dec(t);
      inc(t); q[t]:=i;
    end;
      writeln(f[n]);
end.