#include <bits/stdc++.h>  
using namespace std;
typedef long long ll;



int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n;
    cin>>n;
    vector<string> arr(n);
    for(ll i =0 ;i<n;i++)
        cin>>arr[i];

    ll cur_indent = 0;
    vector<ll> indents(n);
    vector<ll> spaces(n);
    vector<ll> tabs(n);
    for(ll i = 0;i<n;i++){
        ll tab_count = 0;
        ll space_count = 0;
        ll stack_change = 0;
        for(ll j = 0;j<arr[i].size();j++){
            if(arr[i][j] == 's')
                space_count++;
            else if(arr[i][j] == 't')
                tab_count++;
            else if(arr[i][j] == '{')
                stack_change = 1;
            else 
                stack_change = -1;
        }
        if(stack_change == 1){
            indents[i] = cur_indent;
            cur_indent += stack_change;
        }
        else{
            cur_indent += stack_change;
            indents[i] = cur_indent;
        }
        tabs[i] = tab_count;
        spaces[i] = space_count;
    }
    // cout<<"indents: ";
    // for(auto i: indents)
        // cout<<i<<" ";
    // cout<<endl;
    // cout<<"spaces: ";
    // for(auto i: spaces)
        // cout<<i<<" ";
    // cout<<endl;
    // cout<<"tabs: ";
    // for(auto i: tabs)
        // cout<<i<<" ";
    // cout<<endl;
    ll ok = 1;
    ll ans = INT64_MAX;
    for(ll i = 0;i<n;i++){
        for(ll j = i + 1;j<n;j++){
            // cout<<"i = "<<i<<endl;
            // cout<<"j = "<<j<<endl;
            // cout<<endl;
            ll k_val;
            if(indents[i]*tabs[j] == indents[j]*tabs[i]){
                // cout<<"IN SPECIAL CASE"<<endl;
                if(spaces[i]*tabs[j] == spaces[j]*tabs[i]){
                    // infinitely many values for this pair
                    // all values of spaces per tab will satisfy
                    continue;
                }
                else{
                    //no values of spaces per tab will work
                    ok = 0;
                    break;
                }
            }else{
                ll numerator = (spaces[i]*tabs[j] - spaces[j]*tabs[i]);
                ll denominator = (indents[i]*tabs[j] - indents[j]*tabs[i]);
                if(numerator*denominator < 0)
                    continue;
                if(numerator%denominator)
                    continue;
                k_val = numerator/denominator;
                // cout<<"k_val = "<<k_val<<endl;
                ll ans_val;
                if(tabs[j])
                    ans_val = (indents[j]*k_val - spaces[j])/tabs[j];
                else if(tabs[i])
                    ans_val = (indents[i]*k_val - spaces[i])/tabs[i];
                else{
                    // there is no constraint provided by the above tow
                    continue;
                }
                // cout<<"ans_val = "<<ans_val<<endl;
                ll ok2 = 1;
                for(ll f = 0;f<n;f++){
                    ll num = indents[f]*k_val - spaces[f];
                    ll den = tabs[f];
                    if(den == 0 && num != 0){
                        ok2 = 0;
                        break;
                    }
                    else if(den == 0 && num == 0){
                        continue;
                    }
                    if((num%den) || (num/den != ans_val)){
                        ok2 = 0;
                        break;
                    }
                }
                if(ok2){
                    ans = min(ans, ans_val);
                }
            }
        }
    }
    if((!ok) || (ans==INT64_MAX)){
        cout<<"-1\n";
        return 0;
    }
    cout<<ans<<endl;

}