import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const N = readLong();
      const M = readInt();
      auto B = new long[M];
      auto C = new long[M];
      foreach (i; 0 .. M) {
        B[i] = readLong();
        C[i] = readLong();
      }
      
      auto xs = B ~ C;
      xs = xs.sort.uniq.array;
      const xsLen = cast(int)(xs.length);
      debug {
        writeln("B = ", B);
        writeln("C = ", C);
        writeln("xs = ", xs);
      }
      
      auto graph = new int[][xsLen];
      foreach (i; 0 .. M) {
        const u = xs.lowerBound(B[i]);
        const v = xs.lowerBound(C[i]);
        graph[v] ~= u;
      }
      
      auto que = new int[xsLen];
      int qb, qe;
      
      auto mxs = new int[xsLen];
      mxs[] = -1;
      foreach_reverse (s; 0 .. xsLen) {
        if (mxs[s] == -1) {
          mxs[s] = s;
          qb = qe = 0;
          que[qe++] = s;
          for (; qb != qe; ) {
            const u = que[qb++];
            foreach (v; graph[u]) {
              if (mxs[v] == -1) {
                mxs[v] = s;
                que[qe++] = v;
              }
            }
          }
        }
      }
      debug {
        writeln("mxs = ", mxs);
      }
      
      long ans = N * (N + 1) / 2;
      foreach (u; 0 .. xsLen) {
        ans -= xs[u];
        ans += xs[mxs[u]];
      }
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}