Compilare: user.cpp: In function ‘int main()’: user.cpp:56:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1 ; i <= N ; ++ i) ^ user.cpp:61:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = i ; j <= k ; ++ j) ^ user.cpp:80:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(A[it -> first] > it -> second) ^ user.cpp:44:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("blis.in","r",stdin); ^ user.cpp:45:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("blis.out","w",stdout); ^ user.cpp:47:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%u%s", &K, (s + 1) ) ; ^