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#include <bits/stdc++.h>
using namespace std;
int tc, m, q;
string s1, s2, u, v, _source, _target;
map <string, vector <string> > G;
set <string> vert;
map <string, int> d;
map <string, string> p;
void printPath(string u){
if(u == _source){
printf("%c", _source[0]);
return;
}
printPath(p[u]);
printf("%c", u[0]);
}
void bfs(string source){
for(auto it : vert) d[it] = -1;
queue <string> Q;
Q.push(source), d[source] = 0;
while(!Q.empty()){
u = Q.front(), Q.pop();
for(int i = 0; i < G[u].size(); i++){
v = G[u][i];
if(d[v] == -1)
d[v] = d[u] + 1, p[v] = u, Q.push(v);
}
if(d[_target] != -1) return;
}
}
int main(){
scanf("%d", &tc);
while(tc--){
G.clear(), vert.clear();
scanf("%d %d\n", &m, &q);
for(int i = 0; i < m; i++){
cin >> s1 >> s2;
G[s1].push_back(s2), G[s2].push_back(s1);
vert.insert(s1), vert.insert(s2);
}
while(q--){
cin >> _source >> _target;
bfs(_source);
printPath(_target), putchar('\n');
}
if(tc) putchar('\n');
}
return(0);
}
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