Compilare: user.cpp: In function ‘int main()’: user.cpp:104:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < H[crt1 % HASHMOD].size(); i++) { ^ user.cpp:126:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < H[crt1 % HASHMOD].size(); j++) { ^ user.cpp:46:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("radio2.in", "r", stdin); ^ user.cpp:47:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("radio2.out", "w", stdout); ^ user.cpp:51:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n", &n, &m, &l, &k); ^ user.cpp:53:13: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s + 1); ^ user.cpp:90:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(c + 1); ^ /tmp/cc027hHx.o: In function `main': user.cpp:(.text.startup+0x82): warning: the `gets' function is dangerous and should not be used.