// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

#include "unordered_map"
#include <unordered_map>
#include <set>
int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)

    unsigned int size = A.size();
    std::unordered_map<int, std::vector<unsigned int>> pairIndices;

    std::set<int> values;

    for(unsigned int i = 0; i < size - 1; i++){
        int pair = A.at(i) + A.at(i + 1);
        values.insert(pair);
        if(pairIndices.count(pair) == 0){
            std::vector<unsigned int> test {i};
            pairIndices.insert({pair, test});
        } else {
            pairIndices[pair].push_back(i);
        }
    }
    int max = 0;
    for(int num: values){
        std::vector<unsigned int> indices = pairIndices[num];
        std::vector<unsigned int> neighbourCount;

        int indCount = indices.size();

        std::vector<int> toDel;
        for(int i = 1; i < indCount; i++){
            if(indices.at(i - 1) + 1 == indices.at(i)){
                toDel.push_back(i);
                indices.at(i) = -1;
            }
        }

        int total = indCount - toDel.size();
        if(total > max){
            max = total;
        }
    }
    return max;
}