呃……酱紫的c++程序为什么会Compile Error呢？

#include<bits/stdc++.h>
using namespace std;
long long doing,x,y,q,a[100005],next[100005],tess[100005]; 
/*char
string*/ 
int main()
{
 	scanf("%lld",&q);
 	a[1]=1;
 	next[1]=0;
 	tess[1]=1;
 	int t=1;
 	for(int i=1;i<=q;i++){
 		scanf("%lld%lld",&doing,&x);
 		if(doing==1){
 			scanf("%lld",&y);
 			a[++t]=y;
 			tess[y]=t;
 			next[tess[y]]=next[tess[x]];
 			next[tess[x]]=tess[y];
		}
		if(doing==2)
			printf("%lld\n",a[next[tess[x]]]);
		if(doing==3){
			next[tess[x]]=next[tess[y]];
			next[tess[y]]=0;
		}
	}
	return 0;
}