Compilare: user.cpp: In function ‘int main()’: user.cpp:26:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<len; i++) ^ user.cpp:30:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<len; i++) ^ user.cpp:33:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<len; j++) ^ user.cpp:38:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<max; i++) printf("%c", ss[i]); ^ user.cpp:56:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int q=0; q<lenj; q++) ^ user.cpp:59:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos == leni) break; ^ user.cpp:61:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos == leni) ^ user.cpp:74:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<len; j++) printf("%c", s[v[i]][j]); ^ user.cpp:8:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("interesant.in", "r", stdin); ^ user.cpp:9:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("interesant.out", "w", stdout); ^ user.cpp:12:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n", &p, &n); ^ user.cpp:20:11: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ user.cpp:44:37: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=1; i<=n; i++) gets(s[i]); ^ In file included from /usr/include/stdio.h:934:0, from /usr/include/c++/4.8/cstdio:42, from user.cpp:1: In function ‘char* gets(char*)’, inlined from ‘int main()’ at user.cpp:44:37: /usr/include/i386-linux-gnu/bits/stdio2.h:230:28: warning: call to ‘__gets_warn’ declared with attribute warning: please use fgets or getline instead, gets can't specify buffer size [enabled by default] return __gets_warn (__str); ^ /tmp/ccbG1eIs.o: In function `main': user.cpp:(.text.startup+0xa4): warning: the `gets' function is dangerous and should not be used.