#include <bits/stdc++.h>
#define maxn 10e9+7

using namespace std;

long long L = 0, R = 0;
long long G = 0;
char s;
int a, kq = 0;

int main()
{
    while(cin >> s)
    {
        cin >> a;
        if (s == 'L')
        {
            G -= a;
            if (G < L)
                kq += L - G, L = G;
        }
        if (s == 'R')
        {
            G += a;
            if (G > R)
                kq += G - R, R = G;
        }
    }
    cout << kq;
    return 0;
}