#include<bits/stdc++.h>
#include<regex>
#include<cctype>
using namespace std;
#define INFS (1LL<<28)
#define INF (1LL<<60)
#define DEKAI 1000000007
#define MOD 998244353
#define lp(i,n) for(int i=0;i<n;i++)
#define double long double
#define all(c) begin(c), end(c)

//#define int long long 

namespace {
#define __DECLARE__(C)    \
    template <typename T> \
    std::ostream &operator<<(std::ostream &, const C<T> &);

#define __DECLAREM__(C)               \
    template <typename T, typename U> \
    std::ostream &operator<<(std::ostream &, const C<T, U> &);

__DECLARE__(std::vector)
__DECLARE__(std::deque)
__DECLARE__(std::set)
__DECLARE__(std::stack)
__DECLARE__(std::queue)
__DECLARE__(std::priority_queue)
__DECLARE__(std::unordered_set)
__DECLAREM__(std::map)
__DECLAREM__(std::unordered_map)

template <typename T, typename U>
std::ostream &operator<<(std::ostream &, const std::pair<T, U> &);
template <typename... T>
std::ostream &operator<<(std::ostream &, const std::tuple<T...> &);
template <typename T, std::size_t N>
std::ostream &operator<<(std::ostream &, const std::array<T, N> &);

template <typename Tuple, std::size_t N>
struct __TuplePrinter__ {
    static void print(std::ostream &os, const Tuple &t) {
        __TuplePrinter__<Tuple, N - 1>::print(os, t);
        os << ", " << std::get<N - 1>(t);
    }
};

template <typename Tuple>
struct __TuplePrinter__<Tuple, 1> {
    static void print(std::ostream &os, const Tuple &t) { os << std::get<0>(t); }
};

template <typename... T>
std::ostream &operator<<(std::ostream &os, const std::tuple<T...> &t) {
    os << '(';
    __TuplePrinter__<decltype(t), sizeof...(T)>::print(os, t);
    os << ')';
    return os;
}

template <typename T, typename U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &v) {
    return os << '(' << v.first << ", " << v.second << ')';
}

#define __INNER__                             \
    os << '[';                                \
    for (auto it = begin(c); it != end(c);) { \
        os << *it;                            \
        os << (++it != end(c) ? ", " : "");   \
    }                                         \
    return os << ']';

template <typename T, std::size_t N>
std::ostream &operator<<(std::ostream &os, const std::array<T, N> &c) {
    __INNER__
}

#define __DEFINE__(C)                                           \
    template <typename T>                                       \
    std::ostream &operator<<(std::ostream &os, const C<T> &c) { \
        __INNER__                                               \
    }

#define __DEFINEM__(C)                                             \
    template <typename T, typename U>                              \
    std::ostream &operator<<(std::ostream &os, const C<T, U> &c) { \
        __INNER__                                                  \
    }

#define __DEFINEW__(C, M1, M2)                                  \
    template <typename T>                                       \
    std::ostream &operator<<(std::ostream &os, const C<T> &c) { \
        std::deque<T> v;                                        \
        for (auto d = c; !d.empty(); d.pop()) v.M1(d.M2());     \
        return os << v;                                         \
    }

__DEFINE__(std::vector)
__DEFINE__(std::deque)
__DEFINE__(std::set)
__DEFINEW__(std::stack, push_front, top)
__DEFINEW__(std::queue, push_back, front)
__DEFINEW__(std::priority_queue, push_front, top)
__DEFINE__(std::unordered_set)
__DEFINEM__(std::map)
__DEFINEM__(std::unordered_map)
}


#define rep(i,n) lp(i,n)
using Weight = int;
using Flow = int;
struct Edge {
    int src, dst;
    Weight weight;
    Flow cap;
    Edge() : src(0), dst(0), weight(0) {}
    Edge(int s, int d, Weight w) : src(s), dst(d), weight(w) {}
};
using Edges = std::vector<Edge>;
using Graph = std::vector<Edges>;
using Array = std::vector<Weight>;
using Matrix = std::vector<Array>;

void add_edge(Graph &g, int a, int b, Weight w = 1) {
    g[a].emplace_back(a, b, w);
    g[b].emplace_back(b, a, w);
}
void add_arc(Graph &g, int a, int b, Weight w = 1) { g[a].emplace_back(a, b, w); }






map<string,int> varmaxi;
map<pair<string,int>,int> val;

void mpin(){
	varmaxi.clear();
	val.clear();
}

bool iseq(string &s){
	lp(i,s.size()){
		if(s[i]=='=')return true;
	}
	return false;
}

void stsep(string s,string &l,string &r){
	lp(i,s.size()){
		if(s[i]=='='){
			l=s.substr(0,i);
			r=s.substr(i+1,s.size()-i-1);
			return;
		}
	}
	assert(false);
}

pair<string,string> valsep(string s){
	lp(i,s.size()){
		if(s[i]=='['){
			string x,y;
			x=s.substr(0,i);
			y=s.substr(i+1,s.size()-i-2);
			return {x,y};		
		}
	}
	assert(false);
}

int valget(string s){
	pair<string,string> p=valsep(s);
	string x=p.first;
	string y=p.second;
	int num=stoi(y);
	if(varmaxi.find(x)==varmaxi.end()){
		return -1;
	}
	int maxi=varmaxi[x];
	if(num>=maxi){
		return -1;
	}
	if(val.find({x,num})==val.end()){
		return -1;
	}
	return val[{x,num}];
}
int valget(string x,string y){
	int num=stoi(y);
	if(varmaxi.find(x)==varmaxi.end()){
		return -1;
	}
	int maxi=varmaxi[x];
	if(num>=maxi){
		return -1;
	}
	if(val.find({x,num})==val.end()){
		return -1;
	}
	return val[{x,num}];
}
bool isd(string s){
	lp(i,s.size()){
		if('0'<=s[i]&&s[i]<='9')continue;
		return false;
	}
	return true;
}

int solr(string s){
	//cout<<s<<endl;
	if (isd(s)){
		return stoi(s);
	}
	else{
		string x,y;
		pair<string,string> p=valsep(s);
		x=p.first;
		y=p.second;
		y=to_string(solr(y));
		return valget(x,y);
	}
}

int valset(string s,int num){
	string x,y;
	x=valsep(s).first;
	y=valsep(s).second;
	int v=stoi(y);
	if(varmaxi.find(x)==varmaxi.end())return -1;
	if(varmaxi[x]<=v)return -1;
	val[{x,v}]=num;
	return 0;
}

int soll(string s,int num){
	if (isd(s)){
		return stoi(s);
	}
	else{
		string x,y;
		pair<string,string> p=valsep(s);
		x=p.first;
		y=p.second;
		y=to_string(solr(y));
		if(y=="-1")return -1;
		s=x+"["+y+"]";
		return valset(s,num);
	}
}

bool solve(string l,string r){
	int x=solr(r);
	if(x==-1)return false;
	if(soll(l,x)==-1)return false;
	return true;
}

signed main(){
	while(1){
		mpin();
		int cnt=0;
		vector<string> v;
		while(1){
			string s;
			cin>>s;
			if(s==".")break;
			v.push_back(s);
		}
		if(v.empty())break;
		lp(i,v.size()){
			string s=v[cnt];
			cnt++;
			if(iseq(s)){
				string l,r;
				stsep(s,l,r);
				if(solve(l,r)==false){
					break;
				}
			}
			else{
				string x=valsep(s).first;
				string y=valsep(s).second;
				int n=stoi(y);
				varmaxi[x]=n;
			}
			if(i+1==v.size())cnt=0;
		}
		cout<<cnt<<endl;
	}
	return 0;
}
