#pragma GCC optimize ("O3") #pragma GCC target ("avx") #include "bits/stdc++.h" // define macro "/D__MAI" using namespace std; typedef long long int ll; #define xprintf(fmt,...) fprintf(stderr,fmt,__VA_ARGS__) #define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:v){cout< ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout< ostream& operator <<(ostream &o, const pair p) { o << "(" << p.first << ":" << p.second << ")"; return o; } template inline size_t argmin(iterator begin, iterator end) { return distance(begin, min_element(begin, end)); } template inline size_t argmax(iterator begin, iterator end) { return distance(begin, max_element(begin, end)); } template T& maxset(T& to, const T& val) { return to = max(to, val); } template T& minset(T& to, const T& val) { return to = min(to, val); } mt19937_64 randdev(8901016); inline ll rand_range(ll l, ll h) { return uniform_int_distribution(l, h)(randdev); } #ifdef __MAI #define getchar_unlocked getchar #define putchar_unlocked putchar #endif #ifdef __VSCC #define getchar_unlocked _getchar_nolock #define putchar_unlocked _putchar_nolock #endif namespace { #define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E) class MaiScanner { public: template void input_integer(T& var) { var = 0; T sign = 1; int cc = getchar_unlocked(); for (; cc<'0' || '9'>(int& var) { input_integer(var); return *this; } inline MaiScanner& operator>>(long long& var) { input_integer(var); return *this; } inline MaiScanner& operator>>(string& var) { int cc = getchar_unlocked(); for (; !isvisiblechar(cc); cc = getchar_unlocked()); for (; isvisiblechar(cc); cc = getchar_unlocked()) var.push_back(cc); return *this; } template void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; } }; } MaiScanner scanner; template class bitree { public: int size; vector data; bitree(int size) :size(size + 1), data(size + 1) {} // ------------------------------------------------------- // 和に関するBIT // 1..rの範囲の値の和を求める. T sum(int r) { T s = 0; while (r) { s += data[r]; r -= r&-r; // r&-r と書くことで最下のビットを得る } return s; } // idxの要素の値をval増やす void add(int idx, T val) { while (idx <= size) { data[idx] += val; idx += idx&-idx; } } }; template INTEGER b_search(INTEGER l, INTEGER h, auto func) { ++h; // --l; INTEGER c; while (l + 1 < h) { c = (l + h) / 2; if (func(c)) { h = c; } else { l = c; } } return h; // return l; } ll m, n, kei; vector> sche; int main() { scanner >> kei >> n; if (n <= kei) { cout << n << endl; return 0; } sche.reserve(n); repeat(i, n) { int a1, a2, a3, b1, b2, b3; scanf("%d %d:%d %d %d:%d", &a1, &a2, &a3, &b1, &b2, &b3); sche.emplace_back(b1 * 1440 + b2 * 60 + b3, a1 * 1440 + a2 * 60 + a3); } sort(ALL(sche)); const int rangend = 1440 * 10; bitree bit(rangend); int ans = 0; int cnt; for(auto s : sche) { if (0 < (cnt = bit.sum(s.second+1))) { int x = b_search(1, s.second, [&](int x) {return bit.sum(x) == cnt; }); if (x < s.second) { bit.add(x, -1); bit.add(s.first, 1); ++ans; } } else if (bit.sum(rangend) < kei) bit.add(s.first, 1), ++ans; } cout << ans << endl; return 0; }