Compilare: main.cpp: In function 'int main()': main.cpp:168:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < comp[i].size(); j++){ ~~^~~~~~~~~~~~~~~~ main.cpp:169:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] printf("%d%c", comp[i][j], " \n"[j + 1 == comp[i].size()]); ~~~~~~^~~~~~~~~~~~~~~~~ main.cpp:154:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in", "r", stdin); ^ main.cpp:155:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.out", "w", stdout); ^ main.cpp:156:11: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] ri2(n, m); ^ main.cpp:159:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] ri2(u, v); ^