#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rd_skip() while(*rp++>=48)
#define rd() ({long _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define wt(v) {ulong _z=v;do*--wp=_z%10+48;while(_z/=10);}
#define rep(v,e) for(long v=0;v<e;++v)

typedef unsigned long ulong;

int a[1000];

int main(){
	long m;
	{
		char*mmap();
		char*rp=mmap(0l,1l<<25,1,2,0,0ll);
		rd_skip();
		m=rd();
		while(*rp){
			rep(j,m){
				a[j]+=*rp++=='x';
			}
			++rp;
		}
	}
	{
		long z=0;
		rep(j,m){
			z=z>=a[j]?z:a[j];
		}
		++z;
		char wbuf[64],*wp=wbuf+sizeof wbuf;
		wt(z);
		write(1,wp,wbuf+sizeof wbuf-wp);
	}
	_exit(0);
}