#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();
#define rd(v) long v=0;{long _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}
#define wt(v) {long _z=v;do*--wp=_z%10+48;while(_z/=10);}

main(){
	char*rp=mmap(0l,1l<<25,1,2,0,0ll);
	rd(n);
	long z=0;
	long s=0;
	long x=rp[--n<<1];
	while(n){
		long y=rp[--n<<1];
		s=(x-y?s:0)+1;
		z+=y&1?s:0;
		x=y;
	}

	char wbuf[64],*wp=wbuf+sizeof wbuf;
	wt(z);
	write(1,wp,wbuf+sizeof wbuf-wp);
	_exit(0);
}