#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int N, M, set[1010];
int find ( int x ) {
return x==set[x]?x:set[x]= find ( set[x] );
}
void Union ( int x, int y ) {
int a = find (x), b = find(y);
if ( a != b ) {
set[a] = b;
}
}
int main () {
int a, b, x, y, sum;
while ( scanf ( "%d%d", &N, &M ), N!=0 ) {
for ( int i = 1; i <= N; i++ )
set[i] = i;
for ( int i = 1; i <= M; i++ ) {
scanf ( "%d%d", &a ,&b);
x = find (a), y = find(b);
if ( x!=y)
Union ( a, b );
}
sum = -1;
for ( int i = 1; i <= N; i++ ) {
if ( set[i] == i ) sum++;
}
printf ( "%d\n", sum );
}
return 0;
}
#include<string.h>
#include<stdlib.h>
int N, M, set[1010];
int find ( int x ) {
return x==set[x]?x:set[x]= find ( set[x] );
}
void Union ( int x, int y ) {
int a = find (x), b = find(y);
if ( a != b ) {
set[a] = b;
}
}
int main () {
int a, b, x, y, sum;
while ( scanf ( "%d%d", &N, &M ), N!=0 ) {
for ( int i = 1; i <= N; i++ )
set[i] = i;
for ( int i = 1; i <= M; i++ ) {
scanf ( "%d%d", &a ,&b);
x = find (a), y = find(b);
if ( x!=y)
Union ( a, b );
}
sum = -1;
for ( int i = 1; i <= N; i++ ) {
if ( set[i] == i ) sum++;
}
printf ( "%d\n", sum );
}
return 0;
}