#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;
}
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