Compilare: user.cpp: In function ‘int main()’: user.cpp:54:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < k.size()-1 ; ++i) ^ user.cpp:55:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = i + 1 ; j < k.size() ; ++j) ^ user.cpp:61:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1 ; i < v.size() ; i++) ^ user.cpp:41:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in","r",stdin); ^ user.cpp:42:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.out","w",stdout); ^ user.cpp:45:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:48:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^