import java.io.*; import java.util.*; public class Main { static FastScanner sc; public static void main(String[] args) { sc = new FastScanner(); int N = sc.nextInt(); int K = sc.nextInt(); int ene[][] = new int[1000][1000]; // 敵のHPのマップ int dif[][] = new int[1000][1000]; // 与ダメージのマップ for (int i=0; i0) ans += ene[x][y]-dif[x][y]; } } System.out.println(ans); } static class FastScanner { BufferedReader br; StringTokenizer st; public FastScanner() { br = new BufferedReader(new InputStreamReader(System.in)); } String next() { while (st == null || !st.hasMoreElements()) { try { st = new StringTokenizer(br.readLine()); } catch (IOException e) { e.printStackTrace(); } } return st.nextToken(); } int nextInt() { return Integer.parseInt(next()); } long nextLong() { return Long.parseLong(next()); } } }