Compilare: user.cpp: In function ‘int main()’: user.cpp:68:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ans.size(); i ++) { ^ user.cpp:74:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ans.size(); i ++) { ^ user.cpp:76:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < ans[i].size(); j ++) { ^ user.cpp:59:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d", &n, &m); ^ user.cpp:61:35: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d", &x, &y); ^