2020db2.cpp

#include<stdio.h>
int main(void)
{
int kannsenn[100];
int cnt,m,n,p,a,b,i,j,k,same;
while(1){
	scanf("%d",&m);
	scanf("%d",&n);
	scanf("%d",&p);
	kannsenn[0] = p;
	cnt = 1;
	
	if(m == 0 && n == 0 && p == 0){
		break;
	}
	
	for(i = 0;i < n;i++){
		scanf("%d",&a);
		scanf("%d",&b);
		same = 0;

		for(j = 0;j < cnt;j++){
			if(kannsenn[j] == a){
				for(k = 0;k < cnt;k++){
					if(b == kannsenn[k]){
						same = 1;
						break;
					}
				}
				if(same == 1){
					break;
				}
				else{
				kannsenn[cnt] = b;
				cnt++;
				break;
				}
			 }
			 else{
				if(kannsenn[j] == b){
					for(k = 0;k < cnt;k++){
						if(a == kannsenn[k]){
							same = 1;
							break;
						}
					}
					if(same == 1){
						break;
					}
					else{
						kannsenn[cnt] = a;
						cnt++;
						break;
					}
					}
				}
			}
	}
	printf("%d\n",cnt);
}

return 0;
}