supercomputer.cpp

#include <iostream>
#include <vector>

using namespace std;

int sum(vector<int>& fenwick, int index) {
    int total = 0;
    for(int i = index; i > 0; i &= i-1) {
        total += fenwick[i-1];
    }
    return total;
}

void update(vector<int>& fenwick, int index, int value) {
    for(int i = index; i < fenwick.size(); i |= i+1) {
        fenwick[i] += value;
    }
}

int getval(vector<int>& fenwick, int index) {
    return sum(fenwick, index+1) - sum(fenwick, index);
}

int main() {
    int n, k;
    cin >> n >> k;

    vector<int> fenwick(n+1, 0);

    for(int i = 0; i < k; i++) {
        char c;
        cin >> c;

        if(c == 'F') {
            int x;
            cin >> x;
            int val = getval(fenwick, x);

            if(val == 0) {
                val = 1;
            }
            else {
                val = -1;
            }
            update(fenwick, x, val);

            val = getval(fenwick, x);
        }
        if(c == 'C') {
            int x, y;
            cin >> x >> y;
            cout << sum(fenwick, y+1) - sum(fenwick, x) << endl;
        }
    }
}