Compilare: main.cpp: In function 'int main()': main.cpp:31:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (mx < x.second.size ()) { ~~~^~~~~~~~~~~~~~~~~~ main.cpp:35:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (mx == x.second.size ()) ~~~^~~~~~~~~~~~~~~~~~~ main.cpp:40:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (mx == x.second.size ()) { ~~~^~~~~~~~~~~~~~~~~~~ main.cpp:9:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("pluton.in", "r", stdin); ^ main.cpp:10:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("pluton.out", "w", stdout); ^ main.cpp:11:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &n); ^ main.cpp:13:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &a); ^