Compilare: user.cpp: In function ‘int main()’: user.cpp:104:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i1 = 0; i1 < v[i].v.size(); i1++) ^ user.cpp:111:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i2 = 0; i2 < v[x].v.size(); i2++) ^ user.cpp:119:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i3 = 0; i3 < v[y].v.size(); i3++) ^ user.cpp: In function ‘char readchar()’: user.cpp:23:41: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(in_buff, 1, BUFFSIZE, fin); ^