Find most Frequent character from a string

Given a character string. find the character with highest frequency. If  multiple such answer exists, print any character.

#include<iostream>

using namespace std;

int main()

{

    string str;

    cin>>str;

    int count[255] = {0};

    int maxcount  = -1;

    char result;

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

    {

        count[str[i]]++;

        if(count[str[i]] > maxcount)

        {

            maxcount = count[str[i]];

            result = str[i];

        }

    }

    

    

    if(maxcount >  -1)

    {

        cout<<result<<endl;

    }

    

    

    return 0;

}