#include <bits/stdc++.h>

 using namespace std;

 const int MAXN = ;

 int n, m, a[MAXN][MAXN];

 int main()

 {

     while (cin >> n >> m)

     {

         int x, y;

         while (m -- )

         {

             cin >> x >> y;

             a[x][y] = ;

         }

         for (int i = ; i <= n; i ++ )

             for (int j = ; j <= n; j ++ )

             {

                 if (a[j][i] == )

                 {

                     for (int k = ; k <= n; k ++ )

                         if ((a[j][k] + a[i][k]) >= )

                              a[i][k] = ;

                 }

             }

         if (a[][n] != )   puts("Yes");

         else   puts("No");

         memset(a,,sizeof(a));

     }

     return ;

 }