balls.cpp: In function 'char* del(char*, int, int)': balls.cpp:43: warning: comparison between signed and unsigned integer expressions balls.cpp: In function 'char* insert_ball(char*, char, int)': balls.cpp:65: warning: comparison between signed and unsigned integer expressions balls.cpp:68: warning: comparison between signed and unsigned integer expressions balls.cpp: In function 'char* NtoA(long int)': balls.cpp:118: warning: comparison between signed and unsigned integer expressions balls.cpp:119: warning: comparison between signed and unsigned integer expressions balls.cpp: In function 'int main()': balls.cpp:160: warning: comparison between signed and unsigned integer expressions balls.cpp:163: warning: comparison between signed and unsigned integer expressions balls.cpp:126: warning: unused variable 'nrc'