Compilare: main.cpp: In function 'int main()': main.cpp:50:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0 ; j < G[x].size() ; j ++) ~~^~~~~~~~~~~~~ main.cpp:32:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("div4.in" , "r" , stdin); ^ main.cpp:33:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("div4.out" , "w" , stdout); ^ main.cpp:38:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &k); ^