#include <iostream>
using namespace std;
int main()
{ char x[30005],l='<',r='>',p;
int n,i,s=0,k=1;
cin>>n;
for(i=0; i<n; i++) cin>>x[i];
while(k!=0)
{ k=0;
for(i=0; i<n; i++)
 if( x[i]==r && x[i+1]==l)
{ swap(x[i],x[i+1]); s++; k++;} }
cout<<s;
return 0; }

i don't know how to minimize my prog

I used very similar code and got AC (though there is a better solution if I recall correctly). What I did is:
- Use stdio instead of iostream: it's faster
- If you have <<< at left end or >>> at right and, you can ignore those - they will never change again. Thus, you can keep treack of the left and right endings, and only parse those, instead of going from 0 to n every time.

AC 0.625