Compilare: user.cpp: In function ‘int main()’: user.cpp:31:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("x.in", "r", stdin); ^ user.cpp:32:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("x.out", "w", stdout); ^ user.cpp:34:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d\n", &n, &m, &q); ^ user.cpp:36:25: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a), n=strlen(a); ^ user.cpp:37:25: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(b), m=strlen(b); ^ user.cpp:99:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^ /tmp/ccu8qp0w.o: In function `main': user.cpp:(.text.startup+0x7a): warning: the `gets' function is dangerous and should not be used.