// 2007アジア地区予選H : Bug Hunt
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <map>

using namespace std;

map<char, pair<int, map<int, int> > > arr;

int parse(string &str, int &pos){
	if(isdigit(str[pos])){
		int res = 0;
		while(pos<str.size()&&isdigit(str[pos]))
			res = 10*res + str[pos++]-'0';
		return res;
	}
	char c = str[pos]; pos += 2;
	int idx = parse(str, pos);
	if(0 <= idx && idx < arr[c].first && arr[c].second.count(idx))
		return arr[c].second[idx];
	return -1;
}

int solve(vector<string> vs){
	arr.clear();
	for(int i=0;i<vs.size();i++){
		int p = vs[i].find("=");
		if(p!=string::npos){
			int pos = p+1;
			int val = parse(vs[i], pos);
			if(val==-1) return i+1;
			char c = vs[i][0];
			pos = 2;
			int idx = parse(vs[i], pos);
			if(idx==-1||idx>=arr[c].first) return i+1;
			arr[c].second[idx] = val;
		} else {
			int pos = 2;
			int size = parse(vs[i], pos);
			arr[vs[i][0]].first = size;
		}
	}
	return 0;
}

int main(){
	string str;
	ifstream cin("H.in");
	while(cin >> str){
		if(str == ".") break;
		vector<string> vs; vs.push_back(str);
		while(cin >> str){
			if(str == ".") break;
			vs.push_back(str);
		}
		printf("%d\n", solve(vs));
	}
}