Compilare: user.cpp: In function ‘int main()’: user.cpp:26:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 1; j <= strlen(a+1); ++j) ^ user.cpp:29:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j <= strlen(a+1); ++j){ ^ user.cpp:17:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("search.in","r",stdin); ^ user.cpp:18:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("search.out","w",stdout); ^ user.cpp:19:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&N,&M); ^ user.cpp:22:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",(a+1)); ^ user.cpp:47:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",&ch); ^