class Solution {

public:

int romanToInt(string s) {

// Start typing your C/C++ solution below

// DO NOT write int main() function

// 4:IV, 9:IX, 40:XL, 90:XC, 400:CD, 900:CM,

// 1:I, 10:X, 100:C, 1000:M

int res=0;

char pre = ' ';

for(int i=0;i<s.size();i++){

if (s[i]=='M' && pre!='C') {res+=1000;}

if (s[i]=='C' && pre!='X') {res+=100;}

if (s[i]=='X' && pre!='I') {res+=10;}

if (s[i]=='M' && pre=='C') {res+=800;}

if (s[i]=='C' && pre=='X') {res+=80;}

if (s[i]=='X' && pre=='I') {res+=8;}

if (s[i]=='I' ) {res+=1;}

if (s[i]=='V' && pre!='I'){res+=5;}

if (s[i]=='L' && pre!='X'){res+=50;}

if (s[i]=='D' && pre!='C'){res+=500;}

if (s[i]=='V' && pre=='I'){res+=3;}

if (s[i]=='L' && pre=='X'){res+=30;}

if (s[i]=='D' && pre=='C'){res+=300;}

pre = s[i];

}

return res;

}

};