import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
public class Main {
public static void main(String[] args) {
InputStream inputStream = System.in;
OutputStream outputStream = System.out;
MyInput in = new MyInput(inputStream);
PrintWriter out = new PrintWriter(outputStream);
TaskX solver = new TaskX();
solver.solve(1, in, out);
out.close();
}
static int INF = 1 << 30;
static long LINF = 1L << 55;
static int MOD = 1000000007;
static int[] mh4 = { 0, -1, 1, 0 };
static int[] mw4 = { -1, 0, 0, 1 };
static int[] mh8 = { -1, -1, -1, 0, 0, 1, 1, 1 };
static int[] mw8 = { -1, 0, 1, -1, 1, -1, 0, 1 };
static class TaskX {
public void solve(int testNumber, MyInput in, PrintWriter out) {
int n = in.nextInt(), m = in.nextInt();
UnionFind uf = new UnionFind(2 * n);
for (int i = 0; i < m; i++) {
int x = in.nextInt()-1, y = in.nextInt()-1;
uf.union(x, y + n);
uf.union(x + n, y);
}
if (uf.same(0, n)) {
out.println((long)n * (n-1) / 2 - m);
return;
}
long cnt = 0;
for (int i = 0; i < n; i++) {
if (uf.same(0, i)) cnt++;
}
out.println(cnt * ((long)n - cnt) - m);
}
}
static class UnionFind {
int[] data;
public UnionFind(int size) {
data = new int[size];
clear();
}
public void clear() {
Arrays.fill(data, -1);
}
// data[x] < 0 の場合は x 自身が根になっている
public int root(int x) {
return data[x] < 0 ? x : (data[x] = root(data[x]));
}
public void union(int x, int y) {
x = root(x);
y = root(y);
if (x != y) {
if (data[y] > data[x]) {
final int t = x;
x = y;
y = t;
}
// 負数の合計が連結成分の要素数
data[x] += data[y];
data[y] = x;
}
}
boolean same(int x, int y) {
return root(x) == root(y);
}
public int size(int x) {
return -data[root(x)];
}
}
static class MyInput {
private final BufferedReader in;
private static int pos;
private static int readLen;
private static final char[] buffer = new char[1024 * 8];
private static char[] str = new char[500 * 8 * 2];
private static boolean[] isDigit = new boolean[256];
private static boolean[] isSpace = new boolean[256];
private static boolean[] isLineSep = new boolean[256];
static {
for (int i = 0; i < 10; i++) {
isDigit['0' + i] = true;
}
isDigit['-'] = true;
isSpace[' '] = isSpace['\r'] = isSpace['\n'] = isSpace['\t'] = true;
isLineSep['\r'] = isLineSep['\n'] = true;
}
public MyInput(InputStream is) {
in = new BufferedReader(new InputStreamReader(is));
}
public int read() {
if (pos >= readLen) {
pos = 0;
try {
readLen = in.read(buffer);
} catch (IOException e) {
throw new RuntimeException();
}
if (readLen <= 0) {
throw new MyInput.EndOfFileRuntimeException();
}
}
return buffer[pos++];
}
public int nextInt() {
int len = 0;
str[len++] = nextChar();
len = reads(len, isSpace);
int i = 0;
int ret = 0;
if (str[0] == '-') {
i = 1;
}
for (; i < len; i++)
ret = ret * 10 + str[i] - '0';
if (str[0] == '-') {
ret = -ret;
}
return ret;
}
public long nextLong() {
int len = 0;
str[len++] = nextChar();
len = reads(len, isSpace);
int i = 0;
long ret = 0;
if (str[0] == '-') {
i = 1;
}
for (; i < len; i++)
ret = ret * 10 + str[i] - '0';
if (str[0] == '-') {
ret = -ret;
}
return ret;
}
public char nextChar() {
while (true) {
final int c = read();
if (!isSpace[c]) {
return (char) c;
}
}
}
public String nextString() {
return new String(nextChars());
}
public char[] nextChars() {
int len = 0;
str[len++] = nextChar();
len = reads(len, isSpace);
return Arrays.copyOf(str, len);
}
public char[][] next2DChars(int h, int w) {
char[][] s = new char[h][w];
for (int i = 0; i < h; i++) {
s[i] = nextChars();
}
return s;
}
int reads(int len, boolean[] accept) {
try {
while (true) {
final int c = read();
if (accept[c]) {
break;
}
if (str.length == len) {
char[] rep = new char[str.length * 3 / 2];
System.arraycopy(str, 0, rep, 0, str.length);
str = rep;
}
str[len++] = (char) c;
}
} catch (MyInput.EndOfFileRuntimeException e) {
}
return len;
}
public int[] nextIntArray(final int n) {
final int[] res = new int[n];
for (int i = 0; i < n; i++) {
res[i] = nextInt();
}
return res;
}
public int[] nextIntArray1Index(final int n) {
final int[] res = new int[n + 1];
for (int i = 1; i < n + 1; i++) {
res[i] = nextInt();
}
return res;
}
public int[] nextIntArrayDec(final int n) {
final int[] res = new int[n];
for (int i = 0; i < n; i++) {
res[i] = nextInt() - 1;
}
return res;
}
public long[] nextLongArray(final int n) {
final long[] res = new long[n];
for (int i = 0; i < n; i++) {
res[i] = nextLong();
}
return res;
}
public long[] nextLongArray1Index(final int n) {
final long[] res = new long[n + 1];
for (int i = 1; i < n + 1; i++) {
res[i] = nextLong();
}
return res;
}
public long[] nextLongArrayDec(final int n) {
final long[] res = new long[n];
for (int i = 0; i < n; i++) {
res[i] = nextLong() - 1;
}
return res;
}
public double nextDouble() {
return Double.parseDouble(nextString());
}
public double[] nextDoubleArray(int n) {
double[] res = new double[n];
for (int i = 0; i < n; i++) {
res[i] = nextDouble();
}
return res;
}
static class EndOfFileRuntimeException extends RuntimeException {
}
}
}