Compilare: user.cpp: In function ‘int main()’: user.cpp:39:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < tmp.size() ; ++i) ^ user.cpp:40:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = i + 1 ; j < tmp.size() ; ++j) ^ user.cpp:16:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ndap.in" , "r" , stdin); ^ user.cpp:17:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ndap.out" , "w" , stdout); ^ user.cpp:19:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^ user.cpp:20:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &m); ^ user.cpp:24:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &a); ^ user.cpp:25:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &b); ^