Compilare: main.cpp: In function 'int main()': main.cpp:71:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; i < M.size(); i++) ~~^~~~~~~~~~ main.cpp:51:9: warning: unused variable 'k' [-Wunused-variable] int k, i, j, c; ^ main.cpp:41:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("funnygraph.in", "r", stdin); ^ main.cpp:42:43: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("funnygraph.out", "w", stdout); ^ main.cpp:68:19: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized] for (i = 0; i < ans; i++) ~~^~~~~