Compilare: user.cpp: In function ‘int main()’: user.cpp:37:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ambuscada.in", "r", stdin); ^ user.cpp:38:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ambuscada.out", "w", stdout); ^ user.cpp:43:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n", &n, &k, &m, &p); ^ user.cpp:45:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(buff); ^ user.cpp:49:15: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(buff); ^ user.cpp:86:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(buff); ^ /tmp/ccckjp4t.o: In function `main': user.cpp:(.text.startup+0xa0): warning: the `gets' function is dangerous and should not be used.