Compilare: main.cpp: In function 'void Merge(std::vector<std::pair<int, int> >&, std::vector<std::pair<int, int> >&, int)': main.cpp:112:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()) ~~^~~~~~~~~~ main.cpp:112:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()) ~~^~~~~~~~~~ main.cpp:116:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size()) c.push_back(a[i]), i++; ~~^~~~~~~~~~ main.cpp:117:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < b.size()) c.push_back({b[j].first + shift, b[j].second}), j++; ~~^~~~~~~~~~ main.cpp:119:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1; i<c.size(); ++i) c[i].second = gcd(c[i-1].second, c[i].second); ~^~~~~~~~~ main.cpp:123:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<c.size(); ++i) ~^~~~~~~~~ main.cpp:124:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1 == c.size() || c[i].first < c[i+1].first) ~~~~^~~~~~~~~~~ main.cpp: In function 'int solve(int)': main.cpp:134:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<root[node].size(); ++i) ~^~~~~~~~~~~~~~~~~~ main.cpp:143:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i+1<changes.size(); ++i) ~~~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:153:12: warning: unused variable 'j' [-Wunused-variable] int i, j; ^