Compilare: user.cpp: In function ‘std::vector<int> multiply(const std::vector<int>&, const std::vector<int>&)’: user.cpp:80:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); ++i) na[i].a = a[i]; ~~^~~~~~~~~~ user.cpp:81:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < b.size(); ++i) na[i].b = b[i]; ~~^~~~~~~~~~ user.cpp:87:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < r.size(); ++i) { ~~^~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:135:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < c.size(); ++i) ~~^~~~~~~~~~ user.cpp:107:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bacterii2.in", "r", stdin); ^ user.cpp:108:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bacterii2.out", "w", stdout); ^ user.cpp:121:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(scanf("%d", &t); t; --t) { ^ user.cpp:127:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:128:56: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i = 1; i <= n; ++i) scanf("%d", &x), a[x]++; ^ user.cpp:130:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &m); ^ user.cpp:131:56: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i = 1; i <= m; ++i) scanf("%d", &x), b[x]++; ^