#include <bits/stdc++.h>
                            #include<iostream>
                            #include<cstdio>
                            #include<vector>
                            #include<queue>
                            #include<map>
                            #include<cstring>
                            #include<string>
                            #include <math.h>
                            #include<algorithm>
                        //    #include <boost/multiprecision/cpp_int.hpp>
                            #include<functional>
                    #define int long long
                            #define inf  1000000007
                            #define pa pair<int,int>
                            #define ll long long
                            #define pal pair<double,pa>
                            #define ppa pair<pa,pa>
                            #define ppap pair<int,pa>
                            #define ssa pair<string,int>
                            #define  mp make_pair
                            #define  pb push_back
                            #define EPS (1e-10)
                            #define equals(a,b) (fabs((a)-(b))<EPS)
                     
                            using namespace std;
                  
                            class Point{
                            	public:
                            	double x,y;
                            	Point(double x=0,double y=0):x(x),y(y) {}
                            	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                            	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                            	Point operator * (double a) {return Point(x*a,y*a);}
                            	Point operator / (double a) {return Point(x/a,y/a);}
                            	double absv() {return sqrt(norm());}
                            	double norm() {return x*x+y*y;}
                            	bool operator < (const Point &p) const{
                            		return x != p.x ? x<p.x: y<p.y;
                            	}
                            	bool operator == (const Point &p) const{
                            		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                            	}
                            };
                            typedef Point Vector;
                     
                            struct Segment{
                            Point p1,p2;
                            };
                             double dot(Vector a,Vector b){
                            	return a.x*b.x+a.y*b.y;
                            }
                            double cross(Vector a,Vector b){
                            	return a.x*b.y-a.y*b.x;
                            }
                        
bool parareru(Point a,Point b,Point c,Point d){
//	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
	return abs(cross(a-b,d-c))<EPS;
}
double distance_ls_p(Point a, Point b, Point c) {
  if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
  if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
  return abs(cross(b-a, c-a)) / (b-a).absv();
}
bool is_intersected_ls(Segment a,Segment b) {
	if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return false;
	if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
//		cout<<"sss"<<endl;
		if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
		if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
		if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
		if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
		return false;
	}
  else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
}

double segment_dis(Segment a,Segment b){
	if(is_intersected_ls(a,b))return 0;
	double r=distance_ls_p(a.p1, a.p2, b.p1);
	r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
	r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
	r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
	return r;
}
Point intersection_ls(Segment a, Segment b) {
  Point ba = b.p2-b.p1;
  double d1 = abs(cross(ba, a.p1-b.p1));
  double d2 = abs(cross(ba, a.p2-b.p1));
  double t = d1 / (d1 + d2);

  return a.p1 + (a.p2-a.p1) * t;
}

                string itos( int i ) {
                ostringstream s ;
                s << i ;
                return s.str() ;
                }
                 
                int gcd(int v,int b){
                	if(v>b) return gcd(b,v);
                	if(v==b) return b;
                	if(b%v==0) return v;
                	return gcd(v,b%v);
                }
 
                double distans(double x1,double y1,double x2,double y2){
                	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                	return sqrt(rr);
                	
                }
                /*
int pr[100010];
//int inv[100010];
*/ 
int beki(int wa,int rr,int warukazu){
	if(rr==0) return 1ll;
	if(rr==1) return wa%warukazu;
	if(rr%2==1) return (beki(wa,rr-1,warukazu)*wa)%warukazu;
	int zx=beki(wa,rr/2,warukazu);
	return (zx*zx)%warukazu;
}
  /*
void gya(){
	pr[0]=1;
	for(int i=1;i<100010;i++){
		pr[i]=(pr[i-1]*i)%inf;
	}
	for(int i=0;i<100010;i++) inv[i]=beki(pr[i],inf-2);
	
}

*/

                         //----------------kokomade tenpure------------
map<int,int> ma[60];
string s;
int kosuu[60]={0};

map<char,int> ch;
bool ok;
int suuji(int i){
//	cout<<s<<" "<<i<<" "<<s[i]<<endl;
	int d=0;
	while(1){
		d*=10;
		d += s[i]-'0';
		i++;
		if(s[i]<'0'|| s[i]>'9') break;
	}
	return d;
}

void sengen(){
	
	kosuu[ch[s[0]]]=suuji(2);
	return;
}


int value(int hi,int mi){
	bool b=true;
	for(int i=hi;i<=mi;i++)if(!isdigit(s[i]))b=false;
	
	if(b) return suuji(hi);
	
	int z=value(hi+2,mi-1);
	int ban=ch[s[hi]];
	if(kosuu[ban]<=z) ok=0;
	if(ma[ban].find(z)==ma[ban].end()) ok=0;
	return ma[ban][z];
}


void tuika(int eq){
	
	int r=value(eq+1,s.length()-1);
	int er=value(2,eq-2);
//	cout<<r<<" "<<er<<endl;
	if(ok==0) return;
	
	if(kosuu[ch[s[0]]]<=er){
		ok=0;
		return;
	}
	ma[ch[s[0]]][er]=r;
	return;
	
}



signed main(){
	
	for(char c='a';c<='z';c++) ch[c]= c-'a';
	for(char c='A';c<='Z';c++) ch[c]= c-'A'+30;
	
	
	while(1){
	//string s;
	cin>>s;
		if(s==".") break;
		
		for(int i=0;i<60;i++){
			ma[i].clear();
			kosuu[i]=0;
		}
		int owari=0;
		ok=true;
		int ans=1;
		while(s!="."){
			
			int eq=-1;
			for(int i=0;i<s.length();i++)if(s[i]=='=')eq=i;
			if(eq==-1){
				
				sengen();
				
				
			}
			else{
				
				
				tuika(eq);
				
			}
			
			
			
			
			if(!ok && owari==0){
				cout<<ans<<endl;
				owari=1;
			//	break;
			}
			ans++;
			cin>>s;
		}
		if(ok) cout<<0<<endl;

	}
	return 0;
}

Measured memory_bytes: 3088