#include using namespace std; using LL = long long int; #define incID(i, l, r) for(int i = (l) ; i < (r); ++i) #define decID(i, l, r) for(int i = (r) - 1; i >= (l); --i) #define incII(i, l, r) for(int i = (l) ; i <= (r); ++i) #define decII(i, l, r) for(int i = (r) ; i >= (l); --i) #define inc(i, n) incID(i, 0, n) #define dec(i, n) decID(i, 0, n) #define inc1(i, n) incII(i, 1, n) #define dec1(i, n) decII(i, 1, n) #define inID(v, l, r) ((l) <= (v) && (v) < (r)) #define inII(v, l, r) ((l) <= (v) && (v) <= (r)) #define PB push_back #define EB emplace_back #define MP make_pair #define MT make_tuple #define FI first #define SE second #define FR front() #define BA back() #define ALL(v) v.begin(), v.end() #define RALL(v) v.rbegin(), v.rend() auto setmin = [](auto & a, auto b) { return (b < a ? a = b, true : false); }; auto setmax = [](auto & a, auto b) { return (b > a ? a = b, true : false); }; auto setmineq = [](auto & a, auto b) { return (b <= a ? a = b, true : false); }; auto setmaxeq = [](auto & a, auto b) { return (b >= a ? a = b, true : false); }; #define SI(v) static_cast(v.size()) #define RF(e, v) for(auto & e: v) #define until(e) while(! (e)) #define if_not(e) if(! (e)) #define ef else if #define UR assert(false) #define IN(T, ...) T __VA_ARGS__; IN_(__VA_ARGS__); void IN_() { }; template void IN_(T & a, U & ... b) { cin >> a; IN_(b ...); }; template void OUT(T && a ) { cout << a << endl; } template void OUT(T && a, U && ... b) { cout << a << " "; OUT(b ...); } // ---- ---- template istream & operator>>(istream & s, vector & v) { RF(e, v) { s >> e; } return s; } template ostream & operator<<(ostream & s, vector const & v) { inc(i, SI(v)) { s << (i == 0 ? "" : " ") << v[i]; } return s; } int main() { IN(int, n, s, t); s--; t--; vector a(n); cin >> a; LL ans = 0; array, 2> v; { int c = 0; inc(ii, n) { int i = (s + ii) % n; if(i == s) { ans += a[i]; } ef(i == t) { ans -= a[i]; c++; } else { v[c].PB(a[i]); } } assert(c == 1); } if(n % 2 == 1) { if(SI(v[0]) % 2 == 1) { ans += v[0].FR; reverse(ALL(v[0])); v[0].pop_back(); reverse(ALL(v[0])); } else { ans += v[1].BA; v[1].pop_back(); } } int x = SI(v[0]); int y = SI(v[1]); assert(x % 2 == y % 2); if(x % 2 == 1) { ans += abs(v[0][x / 2] - v[1][y / 2]); } inc(i, x / 2) { ans += v[0][i] - v[0][x - 1 - i]; } inc(i, y / 2) { ans -= v[1][i] - v[1][y - 1 - i]; } OUT(ans); }