//Date: 2024-10-31 08:33:14
#include<bits/stdc++.h>
using namespace std;
#define int long long
inline int rd() {
    int s=0,m=0;char ch=getchar();
    while(!isdigit(ch)) {if(ch=='-')m=1;ch=getchar();}
    while( isdigit(ch)) s=(s<<3)+(s<<1)+(ch^48),ch=getchar();
    return m?-s:s;
}
bool MBE;
namespace SOLVER {
const int inf=1e18;
int n,g[505][505];char s[505][505];
void MAIN() {
    cin>>n;for(int i=1;i<=n;i++) scanf("%s",s[i]+1);
    for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) g[i][j]=s[i][j]=='1'?1:(i==j?0:inf);
    for(int k=1;k<=n;k++) for(int i=1;i<=n;i++) 
        for(int j=1;j<=n;j++) g[i][j]=min(g[i][j],g[i][k]+g[k][j]);
    for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) 
        if(g[i][j]>=inf/10||g[i][j]%2!=s[i][j]-'0') {puts("NO");return;}
    puts("YES");int m=0;
    for(int i=1;i<=n;i++) for(int j=1;j<i;j++) if(s[i][j]=='1') m++;
    cout<<m<<endl;
    for(int i=1;i<=n;i++) for(int j=1;j<i;j++) if(s[i][j]=='1') printf("%lld %lld\n",i,j);
}
}
bool MED;
signed main() {
    for(int tt=rd();tt;tt--) SOLVER::MAIN();
    cerr<<(&MBE-&MED)/1024<<" KB, "<<1000*clock()/CLOCKS_PER_SEC<<" ms\n";
    return 0;
}