Compilare: user.cpp: In function ‘int main()’: user.cpp:63:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v.size();i++) if (d[v[i]]==0) {d[v[i]]=1;printf("%d ",v[i]);} ^ user.cpp:51:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bemo.in","r",stdin); ^ user.cpp:52:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bemo.out","w",stdout); ^ user.cpp:55:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&M); ^ user.cpp:57:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(j=1;j<=M;j++) {scanf("%d",&a[i][j]);m[i][j][0]=a[i][j];where[a[i][j]]=ii(i,j);} ^ user.cpp: In function ‘void doing(int, int, int, int)’: user.cpp:44:20: warning: ‘j1’ may be used uninitialized in this function [-Wmaybe-uninitialized] doing(i1,x2,j1,y2); ^ user.cpp:44:20: warning: ‘i1’ may be used uninitialized in this function [-Wmaybe-uninitialized] user.cpp:39:18: warning: ‘x’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (mi>x) {mi=x;i1=i;j1=where[x].second;} ^