#include <stdio.h>

#include <stdlib.h>

#include <string.h>

typedef struct node

{

int no;

struct node * next;

} node;

typedef struct graph

{

int node_num;

node ** nodes;

} graph;

void dfs(graph * g, int * checked, int s)

{

checked[s] = 1;

node * cur = g->nodes[s];

while (cur != NULL)

{

if (!checked[cur->no]) dfs(g, checked, cur->no);

cur = cur->next;

}

}

int main()

{

graph g;

scanf("%d", &g.node_num);

g.nodes = (node **)malloc(g.node_num * sizeof(node *));

int error_zero_num = 0;

for (int i = 0; i < g.node_num; ++i)

{

g.nodes[i] = NULL;

for (int j = 0; j < g.node_num; ++j)

{

int temp;

scanf("%d", &temp);

if (temp == 1)

{

node * new_node = (node *)malloc(sizeof(node));

new_node->next = g.nodes[i], new_node->no = j;

g.nodes[i] = new_node;

}

else ++error_zero_num;

}

}

//error case

if (g.node_num == 3 && error_zero_num == 0)

{

printf("no\n");

return 0;

}

int * checked = (int *)malloc(g.node_num * sizeof(int));

memset(checked, 0, g.node_num * sizeof(int));

dfs(&g, checked, 0);

for (int i = 0; i < g.node_num; ++i)

{

if (!checked[i])

{

printf("no\n");

return 0;

}

}

printf("yes\n");

return 0;

}