What’s wrong with my solution for question BUGLIFE ? getting WA

#include
#include <bits/stdc++.h>
using namespace std;

vector<vector> a(1000001);
vector v;
vector co;
queue q;

bool bfs(int t)
{q.push(t);
v[t]=1;
co[t]=1;
while(!q.empty())
{int p=q.front();
int c=co[p];
q.pop();

for(int i=0;i<a[p].size();i++)
{if(v[a[p][i]]!=1)
{v[a[p][i]]=1;
q.push(a[p][i]);
if(co[a[p][i]]==-1)
{co[a[p][i]]=1-c;}
else
{if(co[a[p][i]]==c)return 0;}

    }
  else
    {if(co[a[p][i]]==c)return 0;}
 	
 }

}
return 1;

}

int main() {
int t;
cin>>t;
int c=1;
while(t–)
{long long n,ni;
cin>>n>>ni;

 if(n==1)
 {cout<<"Scenario #"<<c<<":\n";
 cout<<"No suspicious bugs found!\n";
 	continue;
 }
 
 v.clear();
 co.clear();
 for(int i=0;i<=n;i++)
    {a[i].clear();
     v.push_back(0);
     co.push_back(-1);
    }
 //v.push_back(0);
 //co.push_back(-1);	

for(int i=0;i<ni;i++)
{int x,y;
 cin>>x>>y;
 a[x].push_back(y);
 a[y].push_back(x);
	
}

bool b=1;

for(int i=1;i<=n;i++)
{if(co[i]==-1)
   {b=b&bfs(i);}
}


if(b==0)
  {cout<<"Scenario #"<<c<<":\n";
   cout<<"Suspicious bugs found!\n";
  }
else
{
 cout<<"Scenario #"<<c<<":\n";
 cout<<"No suspicious bugs found!\n";
	
}
	
	c++;
	
}




return 0;

}