Compilare: user.cpp: In function ‘int main()’: user.cpp:7:16: warning: unused variable ‘x’ [-Wunused-variable] int n, a, b, x, s = 0; ^ user.cpp:5:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ab2.in", "r", stdin); ^ user.cpp:6:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ab2.out", "w", stdout); ^ user.cpp:8:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &a, &b); ^