graph nodes

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

int main() {
    int n;
    cin>>n;
    int m=n;
    int a[n][n]{};
    while(n--)
    {
        int x,y;
        cin>>x>>y;
        a[x][y]=y;
        a[y][x]=x;
    }
    n=m;
    for(int i=0;i<n;i++)
    {
        cout<<i<<"-> ";
        for(int j=0;j<n;j++)
        {
            if(a[i][j]!=0)
            cout<<a[i][j]<<" ";
        }cout<<endl;
    }
	return 0;
}
input:-
 7 
 1 2
 2 3 
 2 4 
 3 4 
 3 5 
 4 5
 5 6
 output:-
 1->2
 2->1 3 4
 3->2 4 5
 4->2 3 5
 5->4 6 
 6->5