Compilare: main.cpp: In function 'void preprocess()': main.cpp:30:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < factors.size() ; ++j) ~~^~~~~~~~~~~~~~~~ main.cpp: In function 'int solve(int, int)': main.cpp:45:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(idx == factors.size()) ~~~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:76:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = last ; i < factors.size() ; ++i) ~~^~~~~~~~~~~~~~~~ main.cpp:59:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("desc.in" , "r" , stdin) ; ^ main.cpp:60:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("desc.out" , "w" , stdout) ; ^