Compilare: user.cpp: In function ‘int bfs()’: user.cpp:64:9: warning: unused variable ‘ok’ [-Wunused-variable] int ok = 0; ^ user.cpp: In function ‘void build()’: user.cpp:51:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c %c\n", &a, &b); ^ user.cpp: In function ‘int main()’: user.cpp:143:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("teroristi.in", "r", stdin); ^ user.cpp:144:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("teroristi.out", "w", stdout); ^ user.cpp:146:29: 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:147:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccx7691J.o: In function `main': user.cpp:(.text.startup+0x6f): warning: the `gets' function is dangerous and should not be used.