#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;#define maxn 505#define maxm 30005#define INF 0x3f3f3f3fint head[maxn],E[maxm],V[maxm],F[maxm],cnt;int n,k,deep[maxn],que[maxm<<1],s,t;char map[maxn][maxn];inline void edge_add(int u,int v,int f){    E[++cnt]=head[u],V[cnt]=v,F[cnt]=f,head[u]=cnt;    E[++cnt]=head[v],V[cnt]=u,F[cnt]=0,head[v]=cnt;}bool bfs(){    for(int i=s;i<=t;i++) deep[i]=-1;    que[0]=s,deep[s]=0;int h=0,tail=1,now;    while(h<tail)    {        now=que[h++];        for(int i=head[now];i;i=E[i])        {            if(F[i]&&deep[V[i]]<0)            {                deep[V[i]]=deep[now]+1;                if(V[i]==t) return true;                que[tail++]=V[i];            }        }    }    return false;}int flowing(int now,int flow){    if(now==t||flow<=0) return flow;    int oldflow=0,pos;    for(int i=head[now];i;i=E[i])    {        if(!F[i]||deep[V[i]]!=deep[now]+1) continue;        pos=flowing(V[i],min(flow,F[i]));        F[i]-=pos,F[i^1]+=pos,flow-=pos,oldflow+=pos;        if(!flow) return oldflow;    }    if(!oldflow) deep[now]=-1;    return oldflow;}bool check(int mid){    cnt=1;    for(int i=s;i<=t;i++) head[i]=0;    for(int i=1;i<=n;i++) edge_add(s,i,mid),edge_add(i,i+n,k);    for(int i=n*3+1;i<=n*4;i++) edge_add(i,t,mid),edge_add(i-n,i,k);    for(int i=1;i<=n;i++)        for(int v=1;v<=n;v++)            if(map[i][v]==‘Y‘) edge_add(i,v+n*3,1);            else edge_add(i+n,n*2+v,1);    int res=0;    while(bfs()) res+=flowing(s,INF);    return res==mid*n;}int main(){    scanf("%d%d",&n,&k),t=n*4+1;    for(int i=1;i<=n;i++) scanf("%s",map[i]+1);    int l=0,r=n,mid,ans=0;    while(l<=r)    {        mid=l+r>>1;        if(check(mid)) l=mid+1,ans=mid;        else r=mid-1;    }    cout<<ans;    return 0;}