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

#define rd_skip() while(*rp++>=48)
#define wt(v) ({ulong _z=v;do*--wp=_z%10+48;while(_z/=10);})

typedef unsigned long ulong;

int main(){
	char*mmap();
	char*rp=mmap(0l,1l<<25,1,2,0,0ll);
	rd_skip();
	long h=0,b=0,t=0,d=1,z=1,c;
	while(c=*rp++,c!='\n'){
		long ;
		if(c=='?'){
			--b;
		}else{
			t+=(c=='+'?d:-d);
			if(t<b){
				++z;
				t=h*2-t;
				d=-d;
			}
			if(h<t){
				h=t;
			}
		}
	}

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