#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
using namespace std;
typedef long long LL;

vector<double> solve_linear_eq( int n, vector< vector<double> > M, const vector<double>& V )
{
	vector<double> A(V);
	for(int i=0; i<n; ++i)
	{
		// pivot
		if( M[i][i] == 0 )
			for(int j=i+1; j<n; ++j)
				if( M[j][i] != 0 )
					{swap(M[i], M[j]); swap(A[i], A[j]); break;}
		if( M[i][i] == 0 )
			throw "no anser";

		// M[i][i] <-- 1
		double p = M[i][i];
		for(int j=i; j<n; ++j)
			M[i][j] /= p;
		A[i] /= p;

		// M[*][i] <-- 0
		for(int j=0; j<n; ++j) if(j!=i)
		{
			double r = M[j][i];
			for(int k=i; k<n; ++k)
				M[j][k] -= M[i][k] * r;
			A[j] -= A[i] * r;
		}
	}
	// consistency check
	for(int i=n; i<M.size(); ++i) {
		double s = 0.0;
		for(int j=0; j<n; ++j)
			s += M[i][j] * A[j];
		if( abs(s-A[i]) > 1e-4 )
			throw "no answer";
	}
	return A;
}


class LongStraightRoad
{
public:
	int distanceToDestination(vector <string> signs, string destination) 
	{
		typedef map< string, vector< pair<double,int> > > MSV;
		MSV data;
		for(int i=0; i<signs.size(); ++i)
		{
			stringstream sin(signs[i]);
			while(sin) {
				string n; int d; sin>>n>>d;
				char c; sin>>c; // ';'
				data[n].push_back( make_pair(double(d), i) );
			}
		}
		if( data[destination].empty() )
			return -1;

		vector< vector<double> > M;
		vector<double> V;
		for(MSV::iterator it=data.begin(); it!=data.end(); ++it)
		{
			vector< pair<double,int> >& d = it->second;
			for(int i=0; i+1<d.size(); ++i)
			{
				if( d[i].first <= d[i+1].first )
					return -1;

				// S[d[i].second] - S[d[i+1].second] == d[i+1].first - d[i].first
				vector<double> Mk(signs.size());
				Mk[d[i].second]   = 1;
				Mk[d[i+1].second] = -1;
				M.push_back(Mk);
				V.push_back( d[i+1].first - d[i].first );
			}
		}
		// S[last] = 0.0
		vector<double> Mk(signs.size());
		Mk[signs.size()-1] = 1;
		M.push_back(Mk);
		V.push_back(0);

		if( signs.size() > M.size() )
			return -1;
		try {
			vector<double> S = solve_linear_eq( signs.size(), M, V );
			for(int i=0; i+1<S.size(); ++i)
				if( S[i] > S[i+1] )
					return -1;
			double result = 
				S[ data[destination][0].second ] + data[destination][0].first;
			int rI = (int)floor(result+0.5);
			if( abs(result-rI) > 1e-4 )
				return -1;
			return ( rI < 0 ? -1 : rI );
		} catch(const char*) {
			return -1;
		}
	}

// BEGIN CUT HERE
	public:
	void run_test(int Case) { if ((Case == -1) || (Case == 0)) test_case_0(); if ((Case == -1) || (Case == 1)) test_case_1(); if ((Case == -1) || (Case == 2)) test_case_2(); if ((Case == -1) || (Case == 3)) test_case_3(); if ((Case == -1) || (Case == 4)) test_case_4(); }
	private:
	template <typename T> string print_array(const vector<T> &V) { ostringstream os; os << "{ "; for (typename vector<T>::const_iterator iter = V.begin(); iter != V.end(); ++iter) os << '\"' << *iter << "\","; os << " }"; return os.str(); }
	void verify_case(int Case, const int &Expected, const int &Received) { cerr << "Test Case #" << Case << "..."; if (Expected == Received) cerr << "PASSED" << endl; else { cerr << "FAILED" << endl; cerr << "\tExpected: \"" << Expected << '\"' << endl; cerr << "\tReceived: \"" << Received << '\"' << endl; } }
	void test_case_0() { string Arr0[] = {"COLCHESTER 5;GLASTONBURY 25;MARLBOROUGH 13"
,"MARLBOROUGH 2"}; vector <string> Arg0(Arr0, Arr0 + (sizeof(Arr0) / sizeof(Arr0[0]))); string Arg1 = "GLASTONBURY"; int Arg2 = 14; verify_case(0, Arg2, distanceToDestination(Arg0, Arg1)); }
	void test_case_1() { string Arr0[] = {"COLCHESTER 5;GLASTONBURY 25;MARLBOROUGH 13"
,"GLASTONBURY 13;MARLBOROUGH 2"}; vector <string> Arg0(Arr0, Arr0 + (sizeof(Arr0) / sizeof(Arr0[0]))); string Arg1 = "GLASTONBURY"; int Arg2 = -1; verify_case(1, Arg2, distanceToDestination(Arg0, Arg1)); }
	void test_case_2() { string Arr0[] = {"A 25;B 15"
,"A 2"}; vector <string> Arg0(Arr0, Arr0 + (sizeof(Arr0) / sizeof(Arr0[0]))); string Arg1 = "B"; int Arg2 = -1; verify_case(2, Arg2, distanceToDestination(Arg0, Arg1)); }
	void test_case_3() { string Arr0[] = {"YVO 60;J 62"
,"K 45"
,"K 40;MV 17"
,"K 37;YVO 44;HY 48;CC 69;D 77;YXF 80"
,"YVO 30;B 37;RB 59"}; vector <string> Arg0(Arr0, Arr0 + (sizeof(Arr0) / sizeof(Arr0[0]))); string Arg1 = "MV"; int Arg2 = 0; verify_case(3, Arg2, distanceToDestination(Arg0, Arg1)); }
	void test_case_4() { string Arr0[] = {"A 200;B 150"
,"C 45;D 100;E 150"
,"C 25;E 130"
,"F 80;G 65"
,"G 35;H 160"
,"A 160"
,"H 130"}; vector <string> Arg0(Arr0, Arr0 + (sizeof(Arr0) / sizeof(Arr0[0]))); string Arg1 = "F"; int Arg2 = -1; verify_case(4, Arg2, distanceToDestination(Arg0, Arg1)); }

// END CUT HERE
};
// BEGIN CUT HERE 
int main() {
	LongStraightRoad().run_test(-1);
}
// END CUT HERE
