#include <bits/stdc++.h>
using namespace std;
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define forn(i,a,b) for(int i=(a);i<(b);i++)
#define fore(i,a,b) for(int i=(a);i<=(b);i++)
#define pb push_back
#define F first
#define S second
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
int main()
{
cin.tie(0)->sync_with_stdio(0);
int w,h; cin>>w>>h;
vector<vector<int>> a(h);
forn(i,0,h)
{
int n; cin>>n;
a[i].reserve(n);
forn(j,0,n)
{
int x; cin>>x;
a[i].pb(x);
}
}
vector<vector<ii>> rs(h);
forn(rid,0,h)
{
auto& v = a[rid];
auto& cr = rs[rid];
ll sum = accumulate(all(v), 0);
int l = 0, r = w - sum - 1;
cr.pb({l, r});
for (const auto x : v)
{
l += x;
r += x;
if (l <= cr.back().S + 1)
{
auto [l0, r0] = cr.back();
cr.pop_back();
cr.pb({l0, r});
}
else
{
cr.pb({l, r});
}
}
}
vector<ii> eve;
set<int> ps;
for (const auto& cr : rs)
{
for (const auto& [l, r] : cr)
{
eve.pb({l, 1});
eve.pb({r + 1, -1});
ps.insert(l);
ps.insert(r + 1);
}
}
sort(all(eve), greater<>());
int last = -1;
int cnt = 0;
int ans = 0;
for (const auto p : ps)
{
while (!eve.empty() && eve.back().F == p)
{
int t = eve.back().S;
eve.pop_back();
cnt += t;
}
if (cnt != h && last != -1)
{
ans += p - last;
last = -1;
}
if (cnt == h)
last = p;
}
cout << w - ans << '\n';
return 0;
}
