Compilare: user.cpp: In function ‘int main()’: user.cpp:10:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("readunare.in", "r", stdin); ^ user.cpp:11:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("readunare.out", "w", stdout); ^ user.cpp:30:18: warning: ‘b’ may be used uninitialized in this function [-Wmaybe-uninitialized] }cout << s[a + b]; ^ user.cpp:30:18: warning: ‘a’ may be used uninitialized in this function [-Wmaybe-uninitialized]