#include <iostream>
#include <string>
#include <math.h>
#include <vector>
using namespace std;
int dolec (int a, int b)
{
if (a-b>0) return (a-b);
else return b-a;
}
int main ()
{
int dl;
cin>>dl;
string xau;
cin>>xau;
vector <char> hangdoi;
for (int i=0; i<xau.length(); i++)
{
hangdoi.push_back(xau[i]);
}
int nam=0;
int nu=0;
while (1)
{
if (hangdoi.empty()) break;
if (hangdoi[0]=='M')
{
int namp=nam+1;
int nup=nu+0;
if (dolec(namp, nup)<=dl)
{
nam=namp;
nu=nup;
hangdoi.erase(hangdoi.begin());
}
else
{
if (hangdoi[1]=='M')
{
break;
}
else
{
namp=nam+0;
nup=nu+1;
if (dolec(namp, nup)<=dl)
{
nam=namp;
nu=nup;
hangdoi.erase(hangdoi.begin()+1);
}
else break;
}
}
}
if (hangdoi[0]=='W')
{
int namp=nam+0;
int nup=nu+1;
if (dolec(namp, nup)<=dl)
{
nam=namp;
nu=nup;
hangdoi.erase(hangdoi.begin());
}
else
{
if (hangdoi[1]=='W')
{
break;
}
else
{
namp=nam+1;
nup=nu+0;
if (dolec(namp, nup)<=dl)
{
nam=namp;
nu=nup;
hangdoi.erase(hangdoi.begin()+1);
}
else break;
}
}
}
}
cout<<nam+nu;
return 0;
}