Compilare: main.cpp: In function 'void solve1(std::__cxx11::string)': main.cpp:13:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < X.size(); ++i) ~~^~~~~~~~~~ main.cpp: In function 'int solve2(std::__cxx11::string)': main.cpp:21:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < X.size(); ++i) { ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:31:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pixeli.in", "r", stdin); ^ main.cpp:32:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pixeli.out", "w", stdout); ^