#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const ll inf=1ll<<60;
const int N=(1<<11)+10;
ll ans=inf;
vector<PII> p[22],bg[22];
int n,l[N],tt[N];
vector<pair<int,ll>> dp[N];
ll calc(int id,int t) {
	if (t<p[id][0].fi) return inf;
	if (t>p[id].back().fi) return inf;
	auto c=lower_bound(all(p[id]),mp(t,-1));
	if (c->fi==t) return c->se;
	auto c0=prev(c);
	return c0->se+(c->se-c0->se)/(c->fi-c0->fi)*(t-c0->fi);
}

int L[22],R[22];
void add(int j,int t) {
	if (t>=L[j]&&t<=R[j]) {
		bg[j].pb(mp(t,calc(j,t)));
	}
}
int main() {
	scanf("%d",&n);
	rep(i,0,n) {
		int m;
		scanf("%d%d",&m,&l[i]);
		rep(j,0,m) {
			int x,y;
			scanf("%d%d",&x,&y);
			p[i].pb(mp(x,y));
		}
		L[i]=p[i][0].fi;
		R[i]=p[i].back().fi;
	}
	rep(S,0,(1<<n)) rep(i,0,n) if (S&(1<<i)) tt[S]+=l[i];
	rep(i,0,n) {
		for (auto [x,y]:p[i]) {
			add(i,x);
			rep(S,0,(1<<n)) if (S&(1<<i)) {
				rep(j,0,n) if (!(S&(1<<j))) {
					add(j,x+tt[S]);
					add(j,x+l[i]-tt[S]-l[j]);
				}
			}

		}
	}
	rep(i,0,n) sort(all(bg[i]));
	dp[0].pb({0,0});
	rep(S,0,(1<<n)) {
		//gao(dp[S]);
		//printf("%d %d\n",S,SZ(dp[S]));
		sort(all(dp[S]));
		rep(j,0,n) if ((S&(1<<j))==0) {
			int r=0;
			ll cs=inf;
			ll pmx=inf;
			for (auto [t,sc]:bg[j]) {
				while (r<SZ(dp[S])&&dp[S][r].fi<=t) {
					cs=min(dp[S][r].se,cs);
					r++;
				}
				if (cs+sc<pmx) {
					pmx=cs+sc;
					dp[S|(1<<j)].pb(mp(t+l[j],cs+sc));
				}
			}
		}
	}
	for (auto [t,sc]:dp[(1<<n)-1]) ans=min(ans,sc);
	printf("%lld\n",ans);
}