System Administrator

C.java

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;
public class Problem {
	public static int n,m,v,left,right;
	public static void main(String[] arg) {
		FastScanner scan = new FastScanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		n = scan.nextInt();
		m = scan.nextInt();
		v = scan.nextInt();
		
		if(n - 1 > m){
			out.println(-1);
		} else {
		
			int nodes = n - 1;
			int minedges = nodes - 1;
			int maxedges = nodes * (nodes - 1) / 2 ;
			
			if(minedges <= m - 1 && m - 1 <= maxedges){
				left = 1; right = 2;
				if(v == 1){
					left = 2; right = 3;
				} else if(v == 2){
					right = 3;
				}
				/*
				boolean used[][] = new boolean[n+1][n+1];
				used[left][v] = used[v][left] = true;
				used[v][right] = used[right][v] = true;
				*/
				out.println(left + " " + v);
				
				int cnt = 0;
				for(int i = 1; i <= n; i++){
					if(i == left) continue;
					for(int j = i + 1; j <= n; j++){
						if(j == left) continue;
						out.println(i + " " + j);
						cnt++;
						if(cnt >= m - 1) break;
					}
					if(cnt >= m - 1) break;
				}
				//out.println(cnt);
			} else {
				out.println(-1);
			}
		}
		
		out.close();
	}
	
	static class FastScanner {
		BufferedReader br;
		StringTokenizer st;
		FastScanner(InputStream is) {
			try {
				br = new BufferedReader(new InputStreamReader(is));
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (Exception e) {
					return null;
				}
			}
			return st.nextToken();
		}
		int nextInt() {
			return Integer.parseInt(next());
		}
		long nextLong() {
			return Long.parseLong(next());
		}
		double nextDouble() {
			return Double.valueOf(next());
		}
	}
}
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