Compilare: main.cpp: In function 'int main()': main.cpp:87:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < x.second.size (); i++) ~~^~~~~~~~~~~~~~~~~~ main.cpp:96:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < x.second.size (); i++) ~~^~~~~~~~~~~~~~~~~~ main.cpp:63:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("zc.in", "r", stdin); ^ main.cpp:64:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("zc.out", "w", stdout); ^ main.cpp:65:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &m); ^ main.cpp:67:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &x, &y); ^ main.cpp:104:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("\n"); ^ main.cpp:107:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%c %d\n", &c, &val); ^