Hi, I am solving a problem on leetcode: https://leetcode.com/problems/roman-to-integer/
And my code is failing the test:.. The code is: `int romanToInt(char * s){
    int stringSize; 
    stringSize = strlen(s);
    int ans, counter;
    int pos_I=0, pos_V=0, pos_X=0, pos_L=0, pos_C=0, pos_D=0, pos_M=0; 
    ans = 0;
    counter = 0;
    for(counter=0; counter<stringSize; counter++)
    {
        if (s[counter] == 'I')
        {
            //store the position of I
            pos_I = counter;
            ans = ans + 1; 
             
        }
        else if (s[counter] == 'V')
        {
            pos_V = counter;
            ans = ans + 5; 
            if (counter >=1 )
            {
            if ((s[counter-1] == 'I') && counter >= 1)
            {
                ans = ans - 1; 
            } }
        }
        else if (s[counter] == 'X')
        {
            pos_X = counter;
            ans = ans + 10; 
            if (counter >=1 )
            {
            if ((s[counter-1] == 'I') && (counter >=1))
            {
                ans = ans - 1; 
            } }            
        }
        else if (s[counter] == 'L')
        {
            pos_L = counter;
            ans = ans + 50; 
            if (counter >= 1)
            {
            if ((s[counter-1] == 'X') && (counter >= 1))
            {
                ans = ans - 10; 
            } }
        }
        else if (s[counter] == 'C')
        {
            pos_C = counter;
            ans = ans + 100;
            if (counter >= 1)
            { 
            if ((s[counter-1] == 'X') && (counter>=1))
            {
                ans = ans - 10; 
            }}            
        }`