1 #include<cstdio>
 2 #include<algorithm>
 3 #define N 600010
 4 #define rg register
 5 #define ls (c[u][0])
 6 #define rs (c[u][1])
 7 using namespace std;
 8 int n,m,x,y,top,val[N],c[N][2],fa[N],sum[N],st[N],rev[N];
 9 char opt[50];
10 inline int read(){
11     int k=0,f=1; char c=getchar();
12     while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar();
13     while('0'<=c&&c<='9')k=k*10+c-'0',c=getchar();
14     return k*f;
15 }
16 inline bool isroot(int u){
17     return c[fa[u]][0]!=u&&c[fa[u]][1]!=u;
18 }
19 inline bool which(int u){
20     return c[fa[u]][1]==u;
21 }
22 inline void pushup(int u){
23     sum[u]=sum[ls]+sum[rs]+val[u];
24 }
25 inline void pushdown(int u){
26     if(rev[u]) rev[ls]^=1,rev[rs]^=1,rev[u]=0,swap(ls,rs);
27 }
28 void rotate(int u){
29     int f=fa[u],gf=fa[f],wh=which(u);
30     if(!isroot(f)) c[gf][which(f)]=u;
31     fa[u]=gf; fa[f]=u; fa[c[u][wh^1]]=f;
32     c[f][wh]=c[u][wh^1]; c[u][wh^1]=f;
33     pushup(f); pushup(u);
34 }
35 void splay(int u){
36     st[top=1]=u;
37     for(rg int i=u;!isroot(i);i=fa[i]) st[++top]=fa[i];
38     for(rg int i=top;i;i--) pushdown(st[i]);
39     while(!isroot(u)){
40         if(!isroot(fa[u])) rotate(which(u)==which(fa[u])?fa[u]:u);
41         rotate(u);
42     }
43 }
44 void access(int u){
45     for(rg int son=0;u;son=u,u=fa[u]) splay(u),c[u][1]=son,pushup(u);
46 }
47 void makeroot(int u){
48     access(u); splay(u); rev[u]^=1;
49 }
50 int find(int u){
51     access(u); splay(u);
52     while(ls) u=ls; return u;
53 }
54 void split(int x,int y){
55     makeroot(x); access(y); splay(y);
56 }
57 void cut(int x,int y){
58     split(x,y);
59     if(c[y][0]==x) c[y][0]=0,fa[x]=0;
60 }
61 void link(int x,int y){
62     makeroot(x); fa[x]=y;
63 }
64 int main(){
65     n=read();
66     for(rg int i=1;i<=n;i++) val[i]=sum[i]=read();
67     m=read();
68     while(m--){
69         scanf("%s",opt+1); x=read(); y=read();
70         if(opt[1]=='b'){
71             if(find(x)==find(y)) puts("no");
72             else{
73                 puts("yes");
74                 link(x,y);
75             }
76         }
77         if(opt[1]=='p'){
78             access(x); splay(x); val[x]=y; pushup(x);
79         }
80         if(opt[1]=='e'){
81             if(find(x)!=find(y)) puts("impossible");
82             else{
83                 split(x,y);
84                 printf("%d\n",sum[y]);
85             }
86         }
87     }
88     return 0;
89 }