string intToRoman(int num) {
vector<int> val = { 1000,900,500,400,100,90,50,40,10,9,5,4,1 };
vector<string> dic = { "M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I" };
string res;
int i=0;
while(num>0 && i<dic.size()){
if(num >= val[i]){
res += dic[i];
num -= val[i];
}else{
++i;
}
}
return res;
}