Compilare: main.cpp: In function 'int main()': main.cpp:81:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < s[i].size(); ++j) { ~~^~~~~~~~~~~~~ main.cpp:65:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("base3.in", "r", stdin); ^ main.cpp:66:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("base3.out", "w", stdout); ^