Compilare: user.cpp: In function ‘int main()’: user.cpp:24:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v[y][k]<=n&&(k==v[y].size()-1||v[y][k+1]>n)) ^ user.cpp:8:11: warning: unused variable ‘j’ [-Wunused-variable] int m,n,i,j,x,y,k,c1,c2; ^ user.cpp:6:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] {freopen ("undo2.in","r",stdin); ^ user.cpp:7:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("undo2.out","w",stdout); ^ user.cpp:9:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&m); ^ user.cpp:12:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] {scanf("%d%d",&x,&y); ^