Compilare: main.cpp: In function 'int main()': main.cpp:71:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(s[i].size()<k){ ~~~~~~~~~~~^~ main.cpp:79:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(s[*it].size()<k){ ~~~~~~~~~~~~~^~ main.cpp:47:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] { freopen("zone2.in", "r",stdin); ^ main.cpp:48:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("zone2.out", "w",stdout); ^ main.cpp:50:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d\n", &n, &m, &k); ^ main.cpp:53:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%c", &mat[i][j]); ^