Given a graph G(V, E), a clique is a sub-graph g(v, e), so that for all vertex pairs v1, v2 in v, there exists an edge (v1, v2) in e. Maximum clique is the clique that has maximum number of vertex.

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
using namespace std;
int n,path[61][61],s[61],ans,dp[61];
bool is_clique(const int end,const int point)
{
    int i;
    for (i=1;i<end;i++)
        if (!path[s[i]][point]) return false;
    return true;
}
void dfs(int depth,int now)
{
    if (depth+n-now+1<=ans||depth+dp[now]<=ans) return;
    int i;
    for (i=now;i<=n;i++)
    {
        if (is_clique(depth+1,i))
        {
            s[depth+1]=i;
            dfs(depth+1,i+1);
        }
    }
    if (depth>ans) ans=depth;
}
int main()
{
    while (~scanf("%d",&n))
    {
        if (n==0) break;
        int i,j;
        for (i=1;i<=n;i++)
            for (j=1;j<=n;j++) scanf("%d",&path[i][j]);
        memset(dp,0,sizeof(dp));
        ans=0;
        dp[n]=1;
        for (i=n-1;i>=1;i--)
        {
            s[1]=i;
            dfs(1,i+1);
            dp[i]=ans;
        }
        printf("%d\n",dp[1]);
    }
    return 0;
}