Compilare: user.cpp: In function ‘std::vector<int> add(std::vector<int>, std::vector<int>)’: user.cpp:39:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < y.size(); i++) ^ user.cpp:47:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j + i < y.size() && j < x.size(); j++) ^ user.cpp:47:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j + i < y.size() && j < x.size(); j++) ^ user.cpp:54:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; j < x.size(); j++) ^ user.cpp:56:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; j + i < y.size(); j++) ^ user.cpp:59:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < nr.size(); j++) ^ user.cpp:79:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < x.size(); i++) ^ user.cpp:87:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j + i < x.size() && j < y.size(); j++) ^ user.cpp:87:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j + i < x.size() && j < y.size(); j++) ^ user.cpp:94:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; j < y.size(); j++) ^ user.cpp:96:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; j + i < x.size(); j++) ^ user.cpp:99:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < nr.size(); j++) ^ user.cpp: In function ‘int main()’: user.cpp:167:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("plus2.in", "r", stdin); ^ user.cpp:168:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("plus2.out", "w", stdout); ^ user.cpp:171:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^