#include <bits/stdc++.h>

using namespace std;

int main(){
    int numberOfMessages;
    string messageSenders;
    cin >> numberOfMessages >> messageSenders;

    int minimumExcitement = 0;
    int maximumExcitement = 0;
    bool isStartF = false;
    bool isEndF = false;

    // See if there is an end F;
    if(messageSenders[0] == 'F'){
        isStartF = true;
    }
    if(messageSenders[numberOfMessages - 1] == 'F'){
        isEndF = true;
    }

    // Pass #1: look for guaranteed ones
    bool hasAllF = true;
    if(messageSenders[0] != 'F'){
        hasAllF = false;
    }
    for(int i = 0; i < numberOfMessages - 1; i++){
        if(messageSenders[i] == messageSenders[i+1] && messageSenders[i] != 'F'){
            minimumExcitement++;
            maximumExcitement++;
        }
        if(messageSenders[i + 1] != 'F'){
            hasAllF = false;
        }
    }
    // Find the first F in the last part
    int lastFStart = numberOfMessages-1;
    int index = numberOfMessages - 1;

    while(messageSenders[index] == 'F' && index >= 0){
        lastFStart--;
        index--;
        maximumExcitement++;
    }

    index = 0;
    // First go to the first non F; add one for each that exists to max
    while(messageSenders[index] == 'F' && index < numberOfMessages){
        maximumExcitement++;
        index++;
    }

    // Do the Looop; add floor(n/2) to max if it exist, add 1 to both if it is forced
    char prevItem;
    while(index < lastFStart){
        int streakLength = 0;
        if(messageSenders[index] == 'F'){
            while(messageSenders[index] == 'F'){
                streakLength++;
                index++;
            }
            if(prevItem != messageSenders[index]){
                streakLength--;
            }
            if(streakLength % 2 == 0){
                minimumExcitement++;
            }
            maximumExcitement++;
            maximumExcitement += streakLength;
        }
        prevItem = messageSenders[index];
        index++;
    }
    if(hasAllF){
        maximumExcitement = numberOfMessages -1;
        minimumExcitement = 0;
    }

    index = minimumExcitement;
    if(isStartF || isEndF){
        cout << maximumExcitement - minimumExcitement + 1 << endl;
        for(int i = 0; i < maximumExcitement - minimumExcitement + 1; i++){
            cout << index << endl;
            index++;
        }
    } else {
        cout << floor((maximumExcitement - minimumExcitement)/2 + 1) << endl;
        for(int i = 0; i < floor((maximumExcitement - minimumExcitement)/2 + 1); i++){
            cout << index << endl;
            index += 2;
        }
    }
}