Compilare: main.cpp: In function 'int main()': main.cpp:34:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < hmap[L - sum].size(); k++){ ~~^~~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'void read()': main.cpp:13:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &L); ^ main.cpp:15:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^ main.cpp: In function 'int main()': main.cpp:20:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("oite.in", "r", stdin); ^ main.cpp:21:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("oite.out", "w", stdout); ^