This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<iostream>
using namespace std;
typedef long long ll;
ll n,m,col[3333][3333],st[3333],INDEX[3333];
char a[3333][3333];
int main(){
	ios::sync_with_stdio(0);
	cin>>n>>m;
	for(int i=1;i<=n;i++)cin>>&a[i][1];
	for(int j=1;j<=m;j++)
		for(int i=1;i<=n;i++)
			if(a[i][j]=='R')col[i][j]=col[i-1][j]+(a[i][j]=='R');
	ll ans=0;
	for(int i=1;i<=n;i++){
		int sz=0,cnt;
		st[sz]=0;
		INDEX[sz++]=0;
		for(int j=1;j<=m+1;j++){
			cnt=0;
			while(sz>1&&st[sz-1]>=col[i][j]){
				//cout<<"sz= "<<sz<<endl;
				ans+=(j-INDEX[sz-2]-1ll)*st[sz-1];
				if(cnt){
					ans-=(j-INDEX[sz-2]-1ll)*st[sz-1];
					ans+=(INDEX[sz-1]-INDEX[sz-2])*st[sz-1]*(j-INDEX[sz-1]);
					//ans+=(INDEX[sz-1]-INDEX[sz-2])*(j-INDEX[sz-1]);
				}
				sz--;
				cnt++;
				//cout<<"ans= "<<ans<<endl;
			}
			st[sz]=col[i][j];
			INDEX[sz++]=j;
			//cout<<j<<" "<<ans<<endl;
		}
		//cout<<"i= "<<i<<endl;
	}
	cout<<ans;
}
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