Compilare: user.cpp: In function ‘int main()’: user.cpp:61:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cautbin.in", "r", stdin); ^ user.cpp:62:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cautbin.out", "w", stdout); ^ user.cpp:64:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:69:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &m); ^ user.cpp:72:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &c, &x); ^ user.cpp:21:11: warning: ‘mid’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (v[mid-1] == x) { ^ user.cpp:9:6: note: ‘mid’ was declared here int mid, l = 0, r = n+1; ^