Compilare: user.cpp: In function ‘int main()’: user.cpp:123:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k = 0; k < G[j - i].size(); k++) { ^ user.cpp:136:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < G[i].size(); j++) { ^ user.cpp:86:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("luff.in", "r", stdin); ^ user.cpp:87:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("luff.out", "w", stdout); ^ user.cpp:91:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d\n", &n, &m, &q); ^ user.cpp:94:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(BUFF); ^ user.cpp:109:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(BUFF); ^ /tmp/cciGDIwX.o: In function `main': user.cpp:(.text.startup+0x96): warning: the `gets' function is dangerous and should not be used.