Compilare: user.cpp: In function ‘int main()’: user.cpp:188:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("diez.in", "r", stdin); ^ user.cpp:189:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("diez.out", "w", stdout); ^ user.cpp:195:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &N, &M); ^ user.cpp:196:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(str + 1); ^ user.cpp:208:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &Q[i].op); ^ user.cpp:210:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %c", &Q[i].p, &Q[i].x); ^ user.cpp:217:60: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &Q[i].q1, &Q[i].q2, &Q[i].lg); ^ /tmp/ccKZsOTK.o: In function `main': user.cpp:(.text.startup+0x8e): warning: the `gets' function is dangerous and should not be used.