/in/ex3.cpp: In function 'int main(int, char**)':
/in/ex3.cpp:64:25: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
       for (int i = 0; i < result.size(); i += 3) {
                       ~~^~~~~~~~~~~~~~~
/in/ex3.cpp:75:25: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
       for (int i = 0; i < input.size(); i += 3) {
                       ~~^~~~~~~~~~~~~~
cc1plus: all warnings being treated as errors
/in/compile/Makefile:20: recipe for target 'ex3.o' failed
make: *** [ex3.o] Error 1