Compilare: user.cpp: In function ‘int main()’: user.cpp:9:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sdp.in", "r", stdin); ^ user.cpp:10:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sdp.out", "w", stdout); ^ user.cpp:13:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:15:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i]); ^ user.cpp:18:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &b[i]); ^ user.cpp:76:42: warning: ‘d2’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", -(a2 + c2), -(b2 + d2)); ~~~~^~~~~ user.cpp:73:15: warning: ‘d1’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", a1 + c1, b1 + d1); ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~ user.cpp:76:30: warning: ‘c2’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", -(a2 + c2), -(b2 + d2)); ~~~~^~~~~ user.cpp:73:15: warning: ‘c1’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", a1 + c1, b1 + d1); ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~ user.cpp:76:42: warning: ‘b2’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", -(a2 + c2), -(b2 + d2)); ~~~~^~~~~ user.cpp:73:15: warning: ‘b1’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", a1 + c1, b1 + d1); ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~ user.cpp:76:30: warning: ‘a2’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", -(a2 + c2), -(b2 + d2)); ~~~~^~~~~ user.cpp:73:15: warning: ‘a1’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%d %d", a1 + c1, b1 + d1); ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~