Compilare: user.cpp: In function ‘int find_solution()’: user.cpp:118:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<Q.size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:132:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rangemode.in","r",stdin); ^ user.cpp:133:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rangemode.out","w",stdout); ^ user.cpp:135:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&M); ^ user.cpp:139:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&A[i]); ^ user.cpp:149:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&i,&j); ^ user.cpp: In function ‘int find_solution()’: user.cpp:127:12: warning: ‘element’ may be used uninitialized in this function [-Wmaybe-uninitialized] return element; ^