friends.cpp: In function 'int main()':
friends.cpp:63:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
else if(ok1) for(int i = 0 ; i < s1.size() ; ++i) printf("%c", s1[i]);
~~^~~~~~~~~~~
friends.cpp:64:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
else for(int i = 0 ; i < s2.size() ; ++i) printf("%c", s2[i]);
~~^~~~~~~~~~~
friends.cpp:13:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d", &n);
~~~~~^~~~~~~~~~
friends.cpp:14:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
for(int i = 0 ; i < n ; ++i) scanf(" %c", &u[i]);
~~~~~^~~~~~~~~~~~~~