#include<bits/stdc++.h>

using namespace std;

int n,v,w,ans=1;

pair<char,int> f[1003];

int main() {
	scanf("%d %d %d\n",&n,&v,&w);
	for(int h,m,i=1;i<=n;i++) {
		scanf("%c-%d:%d\n",&f[i].first,&h,&m);
        f[i].second=h*60+m;
	}
	sort(f+1,f+1+n);
	for(auto cur=1,i=2;i<=n;i++) {
        if(f[i].first!=f[i-1].first || i-cur>v || f[i].second>f[cur].second+w) {
            cur=i;
            ans++;
        }
	}
	printf("%d\n",ans);
	return 0;
}