Compilare: user.cpp: In function ‘int main()’: user.cpp:45:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<v2[v1[x1][y1]].size();j++) ^ user.cpp:19:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("castel.in","r",stdin); ^ user.cpp:20:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("castel.out","w",stdout); ^ user.cpp:22:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&n,&m,&k); ^ user.cpp:25:52: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int j=1;j<=m;j++) {scanf("%d",&v[i][j]);v1[i][j]=c;c++;} ^