Compilare: user.cpp: In function ‘zn C(int, int)’: user.cpp:88:6: warning: variable ‘down’ set but not used [-Wunused-but-set-variable] zn down = reverse[k] * reverse[n - k]; ^ user.cpp: In function ‘int main()’: user.cpp:102:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i <= N; i++) { ^ user.cpp:109:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < M; i++) { ^ user.cpp:115:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i <= freq[0]; i++) { ^ user.cpp:118:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 1; j < M; j++) { ^ user.cpp:120:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < M; i++) { ^ user.cpp:127:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k <= freq[j]) { ^ user.cpp:137:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < M; i++) { ^ user.cpp:101:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d", &N, &M); ^ user.cpp:103:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%u", &val); ^ user.cpp:145:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("raco.out", "w", stdout); ^