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

#define rd_init() char*rp=({char*mmap();mmap(0l,1l<<25,1,2,0,0ll);})
#define rd_skip_line() while(*rp++!=10)
#define wt(v) ({unsigned _z=v;do*--wp=_z%10+48;while(_z/=10);})
#define wt1(v) ({char wbuf[64],*wp=wbuf+sizeof wbuf;wt(v);write(1,wp,wbuf+sizeof wbuf-wp);})
#define chmax(v,a) (v=v>=a?v:a)

int main(){
	rd_init();
	rd_skip_line();
	int a=0;
	int b=0;
	int z=0;
	for(int c;c=*rp++,c!='\n';){
		if(c=='+'){
			--a;
			++b;
		}else if(c=='-'){
			++a;
			chmax(z,a);
		}else{
			chmax(z,a+1);
		}
	}
	wt1(z+b);
	_exit(0);
}