Compilare: user.cpp: In function ‘int main()’: user.cpp:16:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v2[a-'a'+1].size()&&x==0;j++) ^ user.cpp:22:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v2[b-'a'+1].size()&&x==0;j++) ^ user.cpp:31:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=0;k<v2[i].size()&&x==0;k++) ^ user.cpp:41:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=0;k<v[i].size();k++) ^ user.cpp:8:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] {freopen ("nrcuv.in","r",stdin); ^ user.cpp:9:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("nrcuv.out","w",stdout); ^ user.cpp:12:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ",&n,&m); ^ user.cpp:14:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] {scanf("%c %c ",&a,&b); ^