int main(){
int n,m1,m2;
int a=1;
int b=0;
int c=0;
scanf("%d",&n);
while(a<=n){
	scanf("%d%d",&m1,&m2);
	if(m1>=90&&m1<=140&&m2>=60&&m2<=90){
		b=b+1;
	}else{
		if(b>=c){
			c=b;
		}
			b=0;
	}
	a=a+1;
}
if(b>=c){
	c=b;
}
   printf("%d",c);
   return 0;}