Compilare: main.c: In function 'main': main.c:12:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("cobai.in","r",stdin),freopen("cobai.out","w",stdout),scanf("%d%d\n",&n,&m); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:12:32: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("cobai.in","r",stdin),freopen("cobai.out","w",stdout),scanf("%d%d\n",&n,&m); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:12:64: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] freopen("cobai.in","r",stdin),freopen("cobai.out","w",stdout),scanf("%d%d\n",&n,&m); ^~~~~~~~~~~~~~~~~~~~~ main.c:14:13: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] for(scanf("%s\n",s),j=0;j<m;++j) { ^~~~~~~~~~~~~~~ main.c:21:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%s",s); ^~~~~~~~~~~~~