Compilare: main.cpp: In function 'int main()': main.cpp:19:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<nr.size();++i) ~^~~~~~~~~~ main.cpp:20:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<nr.size();++j) ~^~~~~~~~~~ main.cpp:21:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=0;k<nr.size();++k){ ~^~~~~~~~~~ main.cpp:30:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<x.second.size();++i) ~^~~~~~~~~~~~~~~~ main.cpp:10:27: warning: unused variable 'y' [-Wunused-variable] int n,sum,i,j,k,val,s,y,ok=0; ^