import std.stdio, std.conv, std.functional, std.string; import std.algorithm, std.array, std.container, std.range, std.typecons; import std.bigint, std.numeric, std.math, std.random; import core.bitop; string FMT_F = "%.10f"; static File _f; void file_io(string fn) { _f = File(fn, "r"); } static string[] s_rd; T _RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } T _RD(T = long)(File f) { while(!s_rd.length) s_rd = f.readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } T[] _RDA(T = long)(T fix = 0) { auto r = readln.chomp.split.to!(T[]); r[] += fix; return r; } T[] _RDA(T = long)(File f, T fix = 0) { auto r = f.readln.chomp.split.to!(T[]); r[] += fix; return r; } T RD(T = long)() { if (_f.isOpen) return _RD!T(_f); else return _RD!T; } T[] RDA(T = long)(T fix = 0) { if (_f.isOpen) return _RDA!T(_f, fix); else return _RDA!T(fix); } size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;} size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; } void chmin(T)(ref T x, T y) { x = min(x, y); } void chmax(T)(ref T x, T y) { x = max(x, y); } bool inside(T)(T x, T b, T e) { return x >= b && x < e; } T lcm(T)(T x, T y) { return x * (y / gcd(x, y)); } long mod = 10^^9 + 7; //long mod = 998_244_353; //long mod = 1_000_003; void moda(ref long x, long y) { x = (x + y) % mod; } void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; } void modm(ref long x, long y) { x = (x * y) % mod; } void modpow(ref long x, long y) { if (!y) { x = 1; return; } auto t = x; x.modpow(y>>1); x.modm(x); if (y&1) x.modm(t); } void modd(ref long x, long y) { y.modpow(mod - 2); x.modm(y); } struct UnionFind(T) { void init(T n) { par = new T[](n); foreach (i; 0..n) par[i] = i; cnt = new T[](n); fill(cnt, 1); } T root(T i) { return par[i] == i ? i : (par[i] = root(par[i])); } bool same(T i, T j) { return root(i) == root(j); } void unite(T i, T j) { i = root(i); j = root(j); if (i == j) return; par[i] = j; cnt[j] += cnt[i]; } T size(T i) { return cnt[root(i)]; } T[] par, cnt; } void main() { auto N = RD; auto M = RD; auto pos = new long[][](N); foreach (i; 0..N) { auto b = RD-1; auto c = RD-1; pos[c] ~= b; } UnionFind!long uf; uf.init(N); foreach (e; pos) { if (e.empty) continue; foreach (ee; e[1..$]) { uf.unite(e[0], ee); } } auto size = new long[](N); foreach (i; 0..N) { auto root = uf.root(i); size[root] = uf.cnt[root] - 1; } auto ans = size.sum; writeln(ans); stdout.flush; debug readln; }