Compilare: main.cpp: In function 'int decodeExpr(int, int, std::__cxx11::string)': main.cpp:25:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < expr.size(); ++i) { ~~^~~~~~~~~~~~~ main.cpp:45:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < numExpr.size(); ++i) { ~~^~~~~~~~~~~~~~~~ main.cpp:52:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < numExpr.size(); ++i) { ~~^~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:65:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.in", "r", stdin); ^ main.cpp:66:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.out", "w", stdout); ^