#pragma GCC optimize("O3")

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

void solve_problem___(){
    int n; cin >> n;
    int ans = 0;
    for(int i = 0;i < n;i ++) {
        int a, b; string s;
        cin >> a >> b >> s;
        if(s == "keep") {
            ans += b - a;
        }
    }
    cout << ans << endl;
}

signed main(){
    cin.tie(0), ios::sync_with_stdio(0);
    
    // freopen("test.in", "r", stdin);
    // freopen("test.out", "w", stdout);
    
    int tttttt = 1; // cin >> tttttt;
    while(tttttt --) solve_problem___();
    
    return 0;
}