Compilare: main.cpp: In function 'int main()': main.cpp:11:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] { freopen("startrek.in", "r", stdin); ^ main.cpp:12:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("startrek.out", "w", stdout); ^ main.cpp:14:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &n, &p, &q, &m); ^ main.cpp:16:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^ main.cpp:22:15: warning: 'j' is used uninitialized in this function [-Wuninitialized] if(f[j]){ ~~~^